I tried AMD K6-233 model 6 3.2 V core processor at 200 MHz (3 x 66 MHz) and the board recognized it as a real AMD K6-200 reducing the V core to 2.87 V (~2.9 V) which is normal operating core voltage for the K6-200 model 6 CPU.

So far, so good, but what about using the two modified BIOSes from TRW site: "10/21/1998-i430HX-2A59FG0BC-00, 137GB HDD and K6-2/3+ patch, ver. 2.9p4" and "05/26/1999-i430HX-2A59FG0BC-00, "TEST" beta BIOS, 137GB HDD and K6-2/3+ patch, ver. 3.0p4"? Do I need to modify the VRM on the board to use these with CPUs with core voltage under 2.9 V (K6-2, K6-III(+)/2+)?

I think the adjustable voltage regulator AS2880 is not very "happy" at 2.8 V output with its heatsink (it gets quite hot), I don't know if this VRM will hold up with even lower voltages (according to datasheet it can go down to 1.2 V).

This motherboard released before the release of K6-2s.
If it has auto voltage switch, it can work without issues.

JSO wrote on 2024-07-18, 05:08:

This motherboard released before the release of K6-2s.
If it has auto voltage switch, it can work without issues.

Yeah, it's not from the latest socket 7 motherboards and now I see that my board revision 1.55 supports AMD K6 model 6 (350 nm) 166 and 200 MHz CPUs with the latest official non-beta BIOS ver. 2.9, but I can't test K6 model 7 (250 nm) "little foot" which needs 2.2 core voltage, 'cause I don't have any of those K6 model7 processors. The output voltage form board's adjustable voltage regulator AS2880 is auto-set by BIOS on POSTing and there's no option for manual core voltage setting in the BIOS menus.

I can try K6-2 and K6-III+ CPUs with one of the modified BIOSes from TRW site, if someone confirms that the VRM on this board can go down "automatically" to at least 2.2 V.

And I still don't have an idea how to clear CMOS on this board.

Probably it will adjust the correct voltage.
You can check it with speedfan. Or in the bios hardware status for the voltage.

To clear the cmos, you can do it in DOS, if you have installed Windows 9x or DOS 6.x - 7.x.

c:\debug

then input the following and restart the machine.

o 70 2E
o 71 FF
quit

JSO wrote on 2024-07-18, 13:58:

To clear the cmos, you can do it in DOS, if you have installed Windows 9x or DOS 6.x - 7.x. […]
Show full quote

To clear the cmos, you can do it in DOS, if you have installed Windows 9x or DOS 6.x - 7.x.

c:\debug

then input the following and restart the machine.

o 70 2E
o 71 FF
quit

Thank you for the suggested clever way for clearing CMOS with DOS DEBUG, JSO! I've never fiddled with motherboards with RTC modules and without clear CMOS jumpers before. This mobo is still in "test stage", so I'm using HDD with DOS 7.1 (the one with Win98SE) attached for the tests. I'll try this hack. Maybe there's some old DOS tool for doing this.

JSO wrote on 2024-07-18, 13:58:

Probably it will adjust the correct voltage.
You can check it with speedfan. Or in the bios hardware status for the voltage.

There is nothing related to CPU's core voltage in the BIOS menus, not even a monitoring section. I think if I try some incompatible s.7 CPU with too low Vcore (K6-III+ for example), it will be fried before I can get in any BIOS menu or boot some OS 😀

As far as I remember "speedfan" was some windows software for temperature monitoring, but how it can help me in checking what minimal CPU core voltage the BIOS can set on boot? Please explain your idea behind using "speedfan".

Hi, analog_programmer,

This is what I know and what I found on-line about the GA-586HX board.

First the BIOS, these patched 2.9p4 and 3.0p4 versions you found on TRW were made by Petr Soucek. Petr is the BIOS patcher who developed the fixes for the Award 32GB and 64GB IDE HDD limit bugs that everybody is using. An archived copy of his work, and details about these “p4” (patch 4) BIOSes for the GA-586HX and GA-586T2, can be found at https://web.archive.org/web/20071114220315/ht … n.cz/petr/bios/

I don’t know what the difference between the latest official 2.9 and the 3.0 beta BIOS is, but the patched “p4” versions look fine to me.

About the “Auto Vcore” on this board, I believe that this is purely done in hardware and that the BIOS is not involved. This Auto Vcore switching will work on single plain voltage CPUs and on dual plain models with 2.8V/2.9V Vcore. So attempting to run lower 2.2V models will quickly fry them! 🙁

I found a great resource about this board at https://web.archive.org/web/20071116073930/ht … .ga586hx.de/en/ with a lot of information about hardware mods needed to get Vcore below 2.8V and to get additional multipliers.

Cheers, Jan

Chkcpu wrote on 2024-07-20, 16:13:

Hi, analog_programmer, […]
Show full quote

Hi, analog_programmer,

This is what I know and what I found on-line about the GA-586HX board.

First the BIOS, these patched 2.9p4 and 3.0p4 versions you found on TRW were made by Petr Soucek. Petr is the BIOS patcher who developed the fixes for the Award 32GB and 64GB IDE HDD limit bugs that everybody is using. An archived copy of his work, and details about these “p4” (patch 4) BIOSes for the GA-586HX and GA-586T2, can be found at https://web.archive.org/web/20071114220315/ht … n.cz/petr/bios/

I don’t know what the difference between the latest official 2.9 and the 3.0 beta BIOS is, but the patched “p4” versions look fine to me.

About the “Auto Vcore” on this board, I believe that this is purely done in hardware and that the BIOS is not involved. This Auto Vcore switching will work on single plain voltage CPUs and on dual plain models with 2.8V/2.9V Vcore. So attempting to run lower 2.2V models will quickly fry them! 🙁

I found a great resource about this board at https://web.archive.org/web/20071116073930/ht … .ga586hx.de/en/ with a lot of information about hardware mods needed to get Vcore below 2.8V and to get additional multipliers.

Cheers, Jan

Thank you very much for all this useful information, Mr. Steunebrink! This archived GA-586HX dedicated site is awesome and unfortunately I've missed it. I think this board will be a lot of modding fun 😀

All the best!

P.S. At least I've suggested correctly, that this board can't provide lower Vcore for the CPU without any hardware modifications and these K6-2(+)/III(+) modified BIOSes are useless without such modifications.

P.S.2 Petr Soucek's archived site is also very interesting with all the info about his BIOS mods.

I gathered some information here:
Gigabyte GA-586HX (Rev. 1.53)

majestyk wrote on 2024-07-20, 17:08:

I gathered some information here:
Gigabyte GA-586HX (Rev. 1.53)

Good job, majestyk! Thanks for the link to your GA-586HX modifications thread. I'll read it carefully later this evening 😀

Some update with tests of this board.

These DOS DEBUG.EXE commands actually kinda work as they reset BIOS settings to "BIOS Defaults":

1o 70 2e
2o 71 ff
3q

This is not exactly the equivalent of hardware invoked "clear CMOS", but better than nothing.

I tested my AMD K6-233 model 6 CPU with switches (SW1 & SW2) set for multiplier of 1.5 and the CPU interpreted it as multiplier of 3.5 running at full speed of 233 MHz (3.5 x 66 MHz) 😀 And here is again some problem with the freeakin' hardware auto-voltage part of this board. The AMD K6-233 model 6 CPU at its full speed of 233 MHz needs 3.2 V for Vcore voltage and the board still provides to this CPU only about 2.9 V for the Vcore voltage thus making the system kinda unstable.

Maybe the fastest intel Pentium P55C (MMX) 233 MHz will run rock stable at full speed (3.5 x 66 MHz) with Vcore of ~2.9 V.

So, at least revision 1.55 of this board doesn't need any BF0 resistor mod for MMX processors with multiplier of 3.5.

For the problem with missing "clear CMOS" jumper option I found a simple "clrcmos.com" DOS tool that seems to work. I'm attaching it here in zip-archive as it may be useful to someone else.

analog_programmer wrote on 2024-07-21, 14:40:

Some update with tests of this board. […]
Show full quote

Some update with tests of this board.

These DOS DEBUG.EXE commands actually kinda work as they reset BIOS settings to "BIOS Defaults":

Copy code to clipboard

1o 70 2e
2o 71 ff
3q

This is not exactly the equivalent of hardware invoked "clear CMOS", but better than nothing.

I tested my AMD K6-233 model 6 CPU with switches (SW1 & SW2) set for multiplier of 1.5 and the CPU interpreted it as multiplier of 3.5 running at full speed of 233 MHz (3.5 x 66 MHz) 😀 And here is again some problem with the freeakin' hardware auto-voltage part of this board. The AMD K6-233 model 6 CPU at its full speed of 233 MHz needs 3.2 V for Vcore voltage and the board still provides to this CPU only about 2.9 V for the Vcore voltage thus making the system kinda unstable.

Maybe the fastest intel Pentium P55C (MMX) 233 MHz will run rock stable at full speed (3.5 x 66 MHz) with Vcore of ~2.9 V.

So, at least revision 1.55 of this board doesn't need any BF0 resistor mod for MMX processors with multiplier of 3.5.

My GA-586HX 1.55 also runs a K6-233 cpu and I'm just thinking about of installing a K6-2 450+

Besides of that I recently got a pair of 64mb but they seem to be Buffered ones. I'm curious if they could be added to the 4x16mb already installed ones.

GuillermoXT wrote on 2024-11-01, 11:18:

My GA-586HX 1.55 also runs a K6-233 cpu and I'm just thinking about of installing a K6-2 450+

AMD K6-2 Chomper Extended (CXT) CPU can run at multiplier of 6 (board set for multi 2). For such a processor this board can give you maximum of 400 MHz for CPU (FSB 66 MHz * multi 6).

The main problem with this mobo is (auto)VRM, which needs some serious hardware modification for CPU core voltages under 2.8 V. For Gigabyte GA-586HX VRM modification details you can check majestyk's thread here: Gigabyte GA-586HX (Rev. 1.53)

GuillermoXT wrote on 2024-11-01, 11:18:

Besides of that I recently got a pair of 64mb but they seem to be Buffered ones. I'm curious if they could be added to the 4x16mb already installed ones.

Intel 430HX chipser supports up to 512MB of ECC or non-ECC EDO/FP RAM, but I have no idea for buffered RAM. Please, give some feedback after you test your buffered RAM modules with the board.

I almost forgot... I have two versions of MR (Microid Research) BIOS dump-files taken from Evergreen Spectra upgrade CDs, but I couldn't test them due to RTC module low battery problem that has befallen my board now.

Here they are for anyone who wants to give them a try: