Chkcpu wrote on 2025-10-19, 14:47:

Ciao Elio, […]
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Ciao Elio,

I did a quick check on your original Acorp A-5VIA3P 12/02/97 Rev C2 BIOS, and it doesn’t support the Cyrix 6x86MX/MII when set to a x4 multiplier. I see this a lot in these late 1997/ early 1998 BIOSes.

The Cx6x86MX changes its CPU Model ID in the Device Identification Register 0 (DIR0) for each supported multiplier setting. The BIOS uses this register to identify the CPU and its multiplier setting, but the Cyrix ID table in your Rev C2 BIOS doesn’t go further than the ID for x3.5.
So when set to x4, the BIOS doesn’t recognize the CPU and can’t initialize it correctly.

The Unicore BIOS upgrade does support Cyrix x4 multiplier correctly. 😀

Cheers, Jan

Ciao, Jan
Thank you very much for your suggestions, actually I suspected that there was a problem when I selected the multi 4X, so much so that I had thought of trying a K6 200, first at a standard frequency 3X 66, then at a reduced frequency 4X 50, just to understand if the multi 4X works, but now thanks to you, I realized that it is a problem of non-recognition of the CPU, due to the BIOS that does not support faster CPUs, so I would avoid changing the CPU for the moment, and I would go directly to the tests with the "Linear Burst" active and the jumper closed.
The next step will then be the BIOS update, and then I would try the frequency of 266 MHz, that is FSB 66 and multi 4X, in this way the CPU would be in the specifications, since I use a Cyrix MII-333, although in reality that CPU is out of the factory as FSB 75 and multi 3.5X, in any case the frequency would be practically the same, 266 MHz against 262.5 MHz, so apart from a slight advantage for the RAM frequency at 75 MHz, for the rest it should be almost the same.
Finally, I'll try to cool the hottest linear controller better, I would try with an additional fan, apart from that I think this motherboard (and most of the VIA), were made with the full support of Cyrix CPUs, which instead shouldn't be on those i430, so if you don't overdo it with the frequencies, I think that around 266 MHz, it can work quite well, in the sense that there should be no problem, due to excessive temperature on the regulators, but beyond and up to 300 MHz, it could be close to the maximum bearable frequency, at least from what I remember.
For these reasons, I think that probably, it is not convenient to use K6-2-400 2.2V CPUs, or other slower 2.2V CPUs, because they pointed out to me, that it would heat up more given the greater difference between input and output current, that is 3.3V-2.2V instead of 3.3V-2.8V.
Greetings Elio

I tried to update the BIOS of the ACORP A-5VIA3P, first I saved on the CF memory card (boot disk), a copy of the BIOS currently present, probably it will be useless, but in case of problems I would avoid downloading it from the internet.
To be on the safe side I turned off and on the PC, and there is the BIOS.old file, which would be the equivalent of VER:C2 dated 12/02/97.
Then I turn off and turn on the PC, and from the folder where the new BIOS is present (unicore), I type AWDFLASH 2A5LDSMB.BIN /py /sn
Unfortunately 😣 shortly after a message 💬 of error appears, "Insufficient Memory!"
I don't know maybe 🤔 there is something that takes up memory, like the CD-ROM drivers or maybe the smartdrv (?), the DOS I use is an MS-DOS VER 5.00 IT, could it be better to use version 6.22?

Changing the memory card, I managed to complete the BIOS update, everything quite simple, now at startup the CPU is seen correctly, like Cyrix MII/IBM 6X86MX-300, clearly 300 is not the real frequency, which would be 3.5X66 that is 233 MHz, and so far so good 😊
The problem that I am trying to solve, is at startup, a message "Primary master hard disk fail" appears, entering the BIOS by pressing "Cancel", there are no dimensions of the CF in MB and the other parameters are all at 0, even if I try from IDE HDD AUTO DETECTION, there is no way to see the values, unfortunately in this way it is impossible for the PC to start.
This way I could see if it starts from floppy, but anyway it would be impossible to access the CF card with DOS, I tried to connect the hard drive, and it is seen correctly, unfortunately 😣 it must be damaged in some sector, because it does not go, that is, it does not start, but it does not report the Primary Master error.
So, I will try the CF cards and the adapter on another PC, if they have no problems, as I imagine, there could be an incompatibility problem with the updated BIOS?

Further update, I checked that the CF cards are working, and in fact it is, on the P3S-1266 QDI they are detected and start correctly, I take note of the values because I will try to insert them manually on the ACORP PC, this means that the error was definitely due to the lack of those three values, which are used to calculate the capacity.
I restart the PC with the ACORP A-5VIA3P and Cyrix MII-333 motherboard (set as MII-300), and enter the BIOS, I manage to enter the three values, save and exit.
Now the PC goes to the next screen, but it freezes on a line, with some dots, in which it says:
Building DMI Pool ………….
The image maybe 🤔 can help in this sense.

I tried other VGA cards, so that the PC detects changes to the configuration, but everything remains as before, that is, it doesn't go on after the second BIOS screen, I don't think you have to wait several minutes, that step should be quite fast, and honestly I don't know what it gets there.
To learn more, I connect the PCI-ISA post card, start the PC and look at the codes displayed, they stop at 63 62, here it would be interesting 🤨 to understand, if those codes can somehow help, the first (63) seems to be somehow connected to the hardware modifications, but it is strange that it does not go beyond that code, since no changes have actually been made, excluding the VGA PCI changes, which in any case have not solved anything.
There would be the possibility of doing a CMOS reset, via jumper on the motherboard, I don't think it can solve this boot problem, then I would like to try to start from floppy 💾, just to understand if it starts (?)

For me it is not complicated to return to the BIOS that I had before, but I would like to try to make this work, not so much for the correct recognition of the CPU, more than anything else for the support of the multi 4X, which I consider the ideal solution for the current CPU, if I had to return to the 3.5X with FSB 66, I would change it with a MII-300, and this MII-333 I would put it in another motherboard.

I just hope that the BIOS chip can be written without problems, I think that chip was never rewritten, since that was the last version available, when the card was for sale, unfortunately 😣 I will be forced to remove it, for reprogramming, but I hope 🤞 that it is not necessary, if the floppy starts I could try to rewrite, the original BIOS.
In this regard, I wonder if it is possible to modify the VER:C2 of 12/02/97, updating only the part related to CPU recognition, so that it can recognize the Cyrix MII with multi 4X.

When the BIOS hangs at Building the DMI pool, please try this:
- Change to another CPU
- Disable the L2 cache in the BIOS
- Remove the BIOS chip and flash the Unicore BIOS in your EEPROM programmer.
This last action will wipe the DMI block and erases any DMI data from the old BIOS. Maybe the new BIOS can build the DMI pool data correctly now.

I hope this helps. If not, I will patch the VER: C2 BIOS but this will take some time.

Jan

Chkcpu wrote on 2025-10-20, 19:06:

When the BIOS hangs at Building the DMI pool, please try this: - Change to another CPU - Disable the L2 cache in the BIOS - Remo […]
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When the BIOS hangs at Building the DMI pool, please try this:
- Change to another CPU
- Disable the L2 cache in the BIOS
- Remove the BIOS chip and flash the Unicore BIOS in your EEPROM programmer.
This last action will wipe the DMI block and erases any DMI data from the old BIOS. Maybe the new BIOS can build the DMI pool data correctly now.

I hope this helps. If not, I will patch the VER: C2 BIOS but this will take some time.

Jan

Ciao Jan
Thank you very much for the suggestions, I will try to do as you suggested, I have already done some tests, such as the CMOS reset, but nothing has changed, maybe 🤔 it could be a BIOS writing problem, usually in the programmer performs a verification after writing, here instead it only writes and that's it.
Anyway this PC, has a problem that I noticed even before, when I save the changes in the BIOS, for example I change the order of the drives, I go out and memorize, the PC makes some beeps and must be turned off, when I turn it back on instead everything is fine.
The codes that are displayed, when the PC beeps, are 41 0d, these are the codes corresponding to the Recovery BIOS, but they usually appear at the first start of the PC, here instead after a Reset, this could be a sign that there may be a malfunctioning BIOS (?).
I will start doing the easiest test, turn off the L2 cache, if it works, then I will try to close the jumper and activate the Linear Burst, hoping it works.
Then I can try with a CPU like a Pentium MMX, just to see how it goes, even if it doesn't work out, I'll try to rewrite the chip, first I'll try with the unicore version, if I don't solve it I'll go back to VER:C2.
If I can't make it work with the unicore version, I'll wait the time necessary to modify the VER:C2, I have other PCs that I can try in the meantime.
Soon if I have news, I will update you, but only in case I manage to start the DOS disk, then I will proceed with Phil's benches.

Greetings Elio

There's news, now it works!
I tried to deactivate the L2 cache, which I had thought of doing, but then I didn't, the PC started the DOS from the CF memory card, but after a short test, I turned it off and went back into the BIOS, to reactivate the L2 cache.
Turned on the PC works!!!
So Jan (thank you very much), one of your suggestions was the right one, now I move on to Phil's benches.
I ran the usual ones from no. 2 to 6, and those from a) to e), almost all were slightly better, so in the measure of a few percentage points, the PC is faster, for now it's fine.
I will continue the tests with the activation of the Linear Burst (with closed jumper), this should give about 5% more speed.
The last test, the one I would say the most important, is with the multi 4X, everything should be ok, the CPU displayed in the first screen of the BIOS, should be a MII/6X86MX-333, from here I will be able to redo the Phil's benches, then later also others.

I did a short test with the ACORP A-5VIA3P and Cyrix MII-333 PC, I changed the jumpers for the multi 4X, which corresponds to a 266 MHz, it works but...
At startup you read the correct wording, Cyrix M II/IBM 6X86MX-333, this was previously identified as 6X86MX-266, the new BIOS has therefore resolved, both the non-recognition (with multi 4X), and the incorrect recognition (MII-300), so so far so good 👌
Now at 266 MHz, the PC starts and switches to the second screen of the BIOS, up to the command prompt C:\, from then on it starts to show some problems, I think we are at most bearable both in frequency and temperature, even if touching the dissi it doesn't seem much warmer, compared to 🫡 at 233 MHz, I don't have a second CPU MII-333 to try, this one I have is a 3.5X 75, so I don't think that working at 4X 66, it can have problems, if you could try 3X 83, but I've never tried the 83 FsB, and I think they could create further problems.
I have to try to improve the cooling of the linear regulators, in particular the one that generates 2.8V, here in this regard, in this board there is no 2.9V, I wonder if by chance this could be the problem, because with 2.8V it could be the CPU that does not work stably (?).
So I think I'll go back to 233 MHz, and try the active Linear Burst, it should give a slight increase in speed, from 2% or 5%, honestly I don't think it's visible, but it's always better than nothing 😇
Later I'll see to change the heatsinks, and add a fan, maybe 🤔 this way I could do the benches, the strange thing is that before at 262.5 MHz the PC worked, then of course there is that with time some components, start to give signs of decay.
To finish, I took back between the paws 🐾, the Soyo SY-5BT with L2 cache chip with missing pin, I had tried to uncover the inner part, milling the plastic of the chip, today after a few attempts, I managed to discover, the broken pin 😑, I have to find a way to increase the uncovered area, currently still small, later I would have to make a bridge 🌉 to the motherboard, to restore contact, I think it is the right way, to get the L2 cache working (512 KB), in the past I had experimented with voltages between 2.2V and 2.8V, if for example you need 2.4V I have to use an additional resistance on the jumper, but in the case of a working L2 cache, it would not be necessary to go below 2.2V, except that you want to put a 2.0V K6-2+ (or less), in that case you should connect the additional resistance, before the corresponding SMD, so that the values are not added, and that the value of the additional one is used.

So before returning to 3.5X 66, I tried again to start and see if I could do some Phil's bench, the only one I managed to complete is Jan's, which starts from the letter S) of the menu.
Obviously 🙄 I knew that there are no scores there, but only info and details on the CPU, on the operating frequency, and more, so the multi 4X works well 😌, but this problem remains to be solved, that the PC crashes, probably as I think, it is possible that it is excessive temperature of the linear controllers, but I can make another attempt, which I had already tried before, that is to leave the 4X and go down from 66 MHz to 60 MHz (FSB), in this way the frequency would be 240 MHz, so slightly higher than the 233 MHz, I don't think the BIOS identifies with this frequency, the CPU at a strange speed, I think it can see it as MII-300 or MII-333, I don't think I see something like MII-320 (or values in the middle between 300 and 333), but who knows we'll see.
If with FSB 60 everything works without problems, it is clear that there is a problem with higher frequencies, if I wanted I could try the FSB 60 with asynchronous PCI, there wouldn't be a big difference, the PCI would go to 32 MHz instead of 30 MHz, but trying it doesn't cost anything.
Theoretically at 240 MHz there might not be any operating problem, I think that at higher frequencies, the slightly lower VCORE, could create problems, for example on the K6-2-550, it has been increased to 2.3V maybe to ensure reliable operation, it is a test that I could do later, on a motherboard with FSB 100 💯.

So, with the further test from a little while ago, set the FSB to 60 MHz and the multi 4X, I started the PC, the CPU is recognized as Cyrix MII-300, I imagined this, however in fact the performance is almost the same, to a 3.5X 66, with the frequency of 240 MHz, there is greater stability, even if after a while and with some bench (I think more demanding), PC blocks occur, a sign that there is a problem, but touching the heat sinks, CPU and linear regulators, I don't even find them too hot, maybe it would take that tenth of volts more, or the linear regulators are at the limit, and maybe their efficiency has decreased, I think they are the factory ones, so they should be more than 25 years old, the motherboard should be from 1997 or at most 1998.
With this I would say that it is not convenient to go beyond 233 MHz, if the card had switching regulators, you could try with a K6-2 400 or 450, here at this point 🧵, I will change the CPU and put back the Cyrix MII-300, this instead I will try it on a ZIDA 5SVA-E card, just to see if it works well at 266 MHz, but from memory I remember trying it, and it seems to me that it had the same problem, that is, it was seen by the BIOS as a 6X86MX-266, so I expect that the 4X does not work, but we will see this later.
For the record, it's not that I'm fixed or I don't have other CPUs to put in, it's just that putting a P2XXMMX on a VIA VPX, doesn't seem right to me, like putting a Cyrix on an i430XX, of course this MII-300 won't be fast enough, but it would only be the PC of the past, which maybe I would use from time to time, to do some tests or bench.

I think I have finished the tests with this PC ACORP A-5VIA3P and Cyrix MII-333, first of all I went back to the settings for a MII-300, then 233 MHz (3.5X 66), any frequency beyond that is unstable or partially unstable (only in some cases).
For this reason, I should put a Cyrix MII-300 CPU, the one of now MII-333, I should try it in another S.7 PC with FSB 100 support, I want to try to see how it goes with other higher FSBs, so I could try 4X 66 and after 2.5X 100, or if I can also 2.5X 103 or 105.
I tried to reconnect the 1.6 GB WD disk 🇬🇧, unfortunately it doesn't work anymore, I try to start Windows, but then at a certain point it stops.
I tried successfully, to activate the Linear Burst, the closed jumper works, but from the results of Phil's bench, it changes very little so it would only go a few tenths better, honestly I would have expected something more, maybe 🤔 it depends on the type of calculations it does, maybe on the integers it could give an advantage of a few percentage points.
A last bench program that I used, is Speedsys 4.70 also here did better than almost nothing, 163.68 against 163.62, for the record I wrote down other scores:
Memory speed index: 168.14
Cache L1 (64 KB) 780.87 MB/s
Cache L2 (512 KB) 159.20 MB/s
Memory Throughput 91.24 MB/s

So I conclude by saying, that the board has benefited from the BIOS update, showing an (imperceptible) improvement, which combined with the active Linear Burst, basically does not change the performance, they remain in my opinion very slow, also strangely it was not possible to make it go to more than 233 MHz, and this is a further step back, but in the past with Intel CPU, I think a 200 MMX, it was slow anyway, so I do not consider this PC as a good example for those who want to replicate a Cyrix PC from the late 90s, I believe that the best solution can be obtained, using a newer MB with FSB 100, in this way you could get from a 333GP, a 350GP or a 366GP, staying below 266 MHz, but raising the FSB to 95 or 100 MHz and using a multi 2.5X (lower).
Possibly for those who have a MII-300, in my opinion it is possible to make it work at 237.5 MHz (2.5X 95), it should with a few more MHz, be identified as MII-350, but it could easily do even 250 MHz (2.5X 100), and it would therefore be a MII-366, the last possibility in case of problems at 250 MHz, would be to make it work at 242.5 MHz (2.5X 97), no I'm sure how it would be seen, I imagine as a MII-350 (?), but if you can go permanently on other frequencies, for example 90 MHz FSB or more than 100, there would be many other possibilities with different multi, 2X for FSB greater than 110.

I found the ZIDA 5SVA-E VER motherboard: 1.0, with CPU Cyrix M II-300GP (66 MHz Bus 3.5X) 2.9 V (Black), there is then a 32 MB SDRAM, a PCI Power Color video card Permedia chip with 4 MB SGRAM, an ISA Sound Blaster MODEL sound card: CT4170, and a 4 GB Fujitsu HD 🇬🇧, almost certainly with Windows 98SE installed.
This motherboard, unlike the ACORP has switching controllers, the chipset is VIA 580 VPX, BIOS Award but at the moment I don't know anything else, the frequency generator is a W48C61-016, theoretically it should get up to 83 MHz, except for unexpected surprises 😱.
Looking at the card, you notice the particular format, with protrusion to accommodate the two chips (Cache L2), indeed in reality only one is a cache chip.
The number of slots would be six in total, three ISA and three PCI, but those that can be used are only five, because one is shared, there are also memory banks for SIMM 72 PIN, but I don't use them, because I keep them aside for PCs that don't have SDRAM memories.
As for the BIOS, I have to check in my notes, if I wrote down the version is the date, and if it correctly identifies the CPU, as Cyrix M II-300GP, or incorrectly indicates Cyrix 6X86MX 266GP.
In this case, I don't think it recognizes the Cyrix CPU using the 4X multi, I shouldn't use this one anyway, since I have the Cyrix 300 GP, and that high multi is only needed for the faster ones.
As soon as 😅 I can, I put this MB on the bench, and start to see if it starts Windows (without problems), theoretically I should have both the USB and PS/2 port, unfortunately 😣 I don't have the original bracket.

According to what I wrote down in my notes 📝, the ZIDA 5SVA-E has an old BIOS, I think it's the original supplied with the MB, on TRW there is only the next version, so I could try to update it, but from my previous experiences, I'll save a copy of the one currently present, maybe 🤔 I'm attaching it here, I don't know who deals with TRW, but you could add it simply by downloading the file that I'll attach.
Let's see what 😨 I read at the start :
5SVA-E REV: 1.0 (9/18/97)
CPU 6X86MX PR266 (invece di M II-300)
07/24/97-580VPX-Prime3C-2A5LDZ1AC-00
The BIOS I remember that it is an AWARD, more info on the MB, the TAG chip is an N341256SJ-12, the sound card turned out to be an SB Vibra 16XV, and on the disk it is installed as I imagined Windows 98SE.
At that time, I did not transcribe the results of the benches, but there could be images or files, stored in some folders on the disk, if I find them I can make a summary to make a comparison with those of ACORP.
I think I'll try this PC, probably in the afternoon, and after running some bench, including those of Phil's, I should save 🛟 of the BIOS currently present, and then I'll update it with the REV:1.1 (present in TRW).
The update should add the recognition of some new CPUs, such as the faster 6X86MX of the PR266, if I had a 2.2V Cyrix CPU I could install it, and try it at various frequencies, but the maximum FSB should be 83 MHz.
In this regard, the frequency generator is a W48C61-01G, I did not find a pdf, so any possible combinations, can be found by trying them, at startup the PC should signal the CPU frequency, from that, using a 2X multi, you can easily understand the FSB.

You can found newest BIOS for your Zida boards here: https://www.zida-bios.com/select-bioses-for-z … with-id-44.html
Clock generator W48C61-01G can do 83 MHz and max. multiplier 3x - later Zida use W48C63 and these can do higher. On K6-2 and newer, there is posibility set up 2x multi, which is interpreted as 6x (I have set my K6-2 300 so it run at 400 MHz, 66x6). For me, setting clock at 75 or 83 MHz is not working with AMD CPUs, but work with Intel Pentium. Other than these (Cyrix, IDT, etc.) I dont have.

Ydee wrote on 2025-10-26, 09:55:

You can found newest BIOS for your Zida boards here: https://www.zida-bios.com/select-bioses-for-z … with-id-44.html
Clock generator W48C61-01G can do 83 MHz and max. multiplier 3x - later Zida use W48C63 and these can do higher. On K6-2 and newer, there is posibility set up 2x multi, which is interpreted as 6x (I have set my K6-2 300 so it run at 400 MHz, 66x6). For me, setting clock at 75 or 83 MHz is not working with AMD CPUs, but work with Intel Pentium. Other than these (Cyrix, IDT, etc.) I dont have.

Thanks a lot
In the past I tried both the K6-2 and the Cyrix M II, I don't remember what frequency the K6-2 had, maybe it was a 350, however in other motherboards, I put some 400 (6X 66), since you need a multi 2X.
As soon as I can do some tests, I'll update you, I hope 🤞 to be able to do some bench, maybe I can get interesting scores.

PC@LIVE wrote on 2025-10-26, 15:51:

Thanks a lot In the past I tried both the K6-2 and the Cyrix M II, I don't remember what frequency the K6-2 had, maybe it was a […]
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Ydee wrote on 2025-10-26, 09:55:

You can found newest BIOS for your Zida boards here: https://www.zida-bios.com/select-bioses-for-z … with-id-44.html
Clock generator W48C61-01G can do 83 MHz and max. multiplier 3x - later Zida use W48C63 and these can do higher. On K6-2 and newer, there is posibility set up 2x multi, which is interpreted as 6x (I have set my K6-2 300 so it run at 400 MHz, 66x6). For me, setting clock at 75 or 83 MHz is not working with AMD CPUs, but work with Intel Pentium. Other than these (Cyrix, IDT, etc.) I dont have.

Thanks a lot
In the past I tried both the K6-2 and the Cyrix M II, I don't remember what frequency the K6-2 had, maybe it was a 350, however in other motherboards, I put some 400 (6X 66), since you need a multi 2X.
As soon as I can do some tests, I'll update you, I hope 🤞 to be able to do some bench, maybe I can get interesting scores.

Ciao Elio,

Thanks to @Ydee’s nice find of the Zida BIOSes, I was able to check the latest 5SVA-E Rev 1.40e BIOS.
I has indeed K6-2 support up to 400MHz, but no K6-III or K6-2+/III+ support.
It is also limited to 32GB IDE drives.

However, this Zida 5SVA-E board is a nice candidate for faster K6-2(+)/III(+) CPUs. It has FSB selections up to 83MHz, an efficient switching mode Vcore supply and probably has Vcore selections from 2.0V to 3.5V in 0.1V steps. Can you check which Vcore controller IC is used on this board?

If 2.0V Vcore is selectable, a K6-2+/III+ at 500MHz should be possible with a patched BIOS on this board.

Cheers, Jan

Chkcpu wrote on 2025-10-26, 16:59:

Ciao Elio, […]
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PC@LIVE wrote on 2025-10-26, 15:51:

Thanks a lot In the past I tried both the K6-2 and the Cyrix M II, I don't remember what frequency the K6-2 had, maybe it was a […]
Show full quote

Ydee wrote on 2025-10-26, 09:55:

You can found newest BIOS for your Zida boards here: https://www.zida-bios.com/select-bioses-for-z … with-id-44.html
Clock generator W48C61-01G can do 83 MHz and max. multiplier 3x - later Zida use W48C63 and these can do higher. On K6-2 and newer, there is posibility set up 2x multi, which is interpreted as 6x (I have set my K6-2 300 so it run at 400 MHz, 66x6). For me, setting clock at 75 or 83 MHz is not working with AMD CPUs, but work with Intel Pentium. Other than these (Cyrix, IDT, etc.) I dont have.

Thanks a lot
In the past I tried both the K6-2 and the Cyrix M II, I don't remember what frequency the K6-2 had, maybe it was a 350, however in other motherboards, I put some 400 (6X 66), since you need a multi 2X.
As soon as I can do some tests, I'll update you, I hope 🤞 to be able to do some bench, maybe I can get interesting scores.

Ciao Elio,

Thanks to @Ydee’s nice find of the Zida BIOSes, I was able to check the latest 5SVA-E Rev 1.40e BIOS.
I has indeed K6-2 support up to 400MHz, but no K6-III or K6-2+/III+ support.
It is also limited to 32GB IDE drives.

However, this Zida 5SVA-E board is a nice candidate for faster K6-2(+)/III(+) CPUs. It has FSB selections up to 83MHz, an efficient switching mode Vcore supply and probably has Vcore selections from 2.0V to 3.5V in 0.1V steps. Can you check which Vcore controller IC is used on this board?

If 2.0V Vcore is selectable, a K6-2+/III+ at 500MHz should be possible with a patched BIOS on this board.

Cheers, Jan

Ciao Jan
So the link is very interesting, because it contains a version later than the one on TRW, there strangely there was only version 1.1, however I would update it with version 1.40, which should be the last one released by ZIDA, I don't think there are correct versions of this for CPU support K6+, or for HD greater than 32 GB 🇬🇧
So I will say, the first step will be the saving 🛟 of the BIOS currently present (1.0), although I saw that in the ZIDA site, there is also that.
After that, I will update to version 1.40, and with that I think I would have solved, the currently visible problems, such as the incorrect recognition of the Cyrix M II-300 (6X86-266), then I can try the multi 4X, I think there should be no problem, if I lower the FSB from 66 to 60 MHz.
In case of success, I could change CPU with the Cyrix M II-333, using the FSB at 66 MHz, for the moment I will not use FSB 75 or 83.
Looking at the manual, the VCORE 2.0V selection is not there, but in my opinion it is possible to get it, removing all the jumpers, alternatively you can try to see if moving the JP9 jumper, from 3-4 to 1-2, you get 2.1V, if so, I would say that it would be quite safe, that you can go down to 2.0V, without modifying the resistances or making HW modifications.
Regarding the IC controller chip, it should be a HIP6008CB, I think it's quite common for the period of these MB, I don't know if it can go below 2.0V, but anyway if it reaches 2.0V, it's already great.
Greetings

Ciao Elio,

The HIP6008CB controller is what I expected as well, and it can regulate the Vcore from 2.0V to 3.5V in 0.1V increments. Here is the datasheet.

The table that shows the Ouput Voltage programming is at page 6.
Looking at the page you posted from the MB user manual, this should be the jumper connections to the VID inputs on the HIP6008CB:

JP9/1-2 -> VID0
JP9/3-4 -> VID1
JP9/5-6 -> VID2
JP9/7-8 -> VID3

Setting a jumper will pull a VID input low.
In other words, all JP9 jumpers OFF will generate 2.0V.
Placing jumper JP9/1-2 will add 0.1V
Placing jumper JP9/3-4 will add 0.2V
Placing jumper JP9/5-6 will add 0.4V
Placing jumper JP9/7-8 will add 0.8V

So with these 4 jumpers, all 16 Vcore settings according the table can be made.
And of course the JP8 jumpers block has to be at position 1-2 for dual-voltage CPUs.

I will look if a further 5SVA-E BIOS upgrade is available, or can be made.

Jan

Chkcpu wrote on 2025-10-26, 18:19:

Ciao Elio, […]
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Ciao Elio,

The HIP6008CB controller is what I expected as well, and it can regulate the Vcore from 2.0V to 3.5V in 0.1V increments. Here is the datasheet.

The attachment HIP6008CB.pdf is no longer available

The table that shows the Ouput Voltage programming is at page 6.
Looking at the page you posted from the MB user manual, this should be the jumper connections to the VID inputs on the HIP6008CB:

JP9/1-2 -> VID0
JP9/3-4 -> VID1
JP9/5-6 -> VID2
JP9/7-8 -> VID3

Setting a jumper will pull a VID input low.
In other words, all JP9 jumpers OFF will generate 2.0V.
Placing jumper JP9/1-2 will add 0.1V
Placing jumper JP9/3-4 will add 0.2V
Placing jumper JP9/5-6 will add 0.4V
Placing jumper JP9/7-8 will add 0.8V

So with these 4 jumpers, all 16 Vcore settings according the table can be made.
And of course the JP8 jumpers block has to be at position 1-2 for dual-voltage CPUs.

I will look if a further 5SVA-E BIOS upgrade is available, or can be made.

Jan

Ciao Jan
Thank you very much, yes in fact it is as I thought, so without jumper it should be 2.0V, and with the jumper on 1-2 I should have 2.1V.
Well then if I were to find a more updated BIOS, I would use that instead of the 1.40.
Greetings