VOGONS


First post, by vintagely

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Hi, i just purchased from ebay for 10$ a K6-2 AFR 400 Mhz that can do 6x multiplier on my 66 mhz socket 7 board here

https://www.ultimateretro.net/motherboard/manual/34148.pdf

Now, before i get my hands on my brand new (?) CPU, i would like to know:

- where i can locate and identify VRM on my board to do some temperature testing or see if it can sustain lots of Amps while running at 400 mhz and 2.5v (which is the lowest my motherboard can do on vcore)
- since im running a pentium 200 mmx cpu right now, i would like to know in case AMD k6-2 is not gonna work on my system, if i can use a pentium 233 MMX unlocking the 1,5x to 3,5x multiplier trick, or there is undocumented vcore voltage and/or jumper settings to increase the 66 mhz bus to like 75 mhz/83 mhz (just for testing purposes not for long term use).
My purpose is to squeeze the most out of this board, as far as i can.

My hardware:

pentium 200 MMX
2x32 mb edo dram (total 64 MB)
S3 trio 64V2 1 MB PCI
3dfx Voodoo 2 12 mb
3Com ethernet card PCI
ps/2 keyboard
ps/2 mouse
Yamaha opl-3 sax audio ISA card
windows 98se
startech socket 7/370 fan on the cpu (can dissipate up to pentium III heat so no issues on this side, but the VRM is my first concern right now).

Reply 1 of 13, by asdf53

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The voltage regulators are easy to spot, they are close to the CPU socket and look like this: https://en.wikipedia.org/wiki/TO-220 or this: https://en.wikipedia.org/wiki/TO-263
You can touch their metal tab to see how hot they're getting. Depending on the type, you can also screw a metal heatsink on them through the hole.

For discovering undocumented FSB settings, locate the clock generator chip (it's near the FSB jumpers) and google the model number to see if there's a data sheet. This would then contain the pins that you need to set.

But no idea about discovering undocumented vcore settings.

if i can use a pentium 233 MMX unlocking the 1,5x to 3,5x multiplier trick

What do you mean? Using the Pentium 200 at 233 MHz? Most Pentium MMX are multiplier locked, I have a MMX 200 and it doesn't work with 3.5x. I believe the best you can do is getting a MMX 233 and overclock using FSB.

Last edited by asdf53 on 2022-08-06, 14:02. Edited 1 time in total.

Reply 2 of 13, by vintagely

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The one marked with the arrow? D-882Y? Then it should have already an heatsink attached to it... too bad as you can see that there is the voodoo 2 basically touching it preventing some airflow to come from CPU heatsink(with some isolating tape i put there on a second thought(that pci slot is the only slot where i can insert the card).

So i guess installing the AMD k6-2 and enabling 400 mhz frequency @ 2.5v the result will likely be:

1) the tape would probably melt
2) the VRM would explode/fail/melt
3) some heat will go to the voodoo 2 probably damaging that too

oh i get the situation now.

I will try to stress test the Pentium 200 mmx and report back the maximum temperature the VRM heatsink will reach on the worst situation...

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Reply 3 of 13, by asdf53

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That's a very big heatsink, I wouldn't worry too much. You also have that big CPU cooler near it. Just let it run with the K6-2 and keep your finger on the heatsink, it's only a problem if it gets so hot that you can barely touch it. Also remember that most boards have two or more of these.

I have a Socket 7 board that has two regulators with no heatsink at all. These get insanely hot, so hot that the metal tab on one of them turned brown over time, and the PCB around them gets to 85 degrees celsius.

Reply 4 of 13, by vintagely

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asdf53 wrote on 2022-08-06, 13:53:

That's a very big heatsink, I wouldn't worry too much. You also have that big CPU cooler near it. Just let it run with the K6-2 and keep your finger on the heatsink, it's only a problem if it gets so hot that you can barely touch it. Also remember that most boards have two or more of these.

I have a Socket 7 board that has two regulators with no heatsink at all. These get insanely hot, so hot that the metal tab on one of them turned brown over time, and the PCB around them gets to 85 degrees celsius.

Glad to hear that thanks! i see there is only one attached to the heatsink but right next to the regulator on the pcb there is another set of three pins. that is probably an unused slot for another regulator maybe??

That being said, it's a shame there is that Voodoo 2 so close to the regulator heatsink i will try to get a better solution for it. My concern anyway was if the regulator was rated for only 5A or something like that and will wear faster than normal...

Reply 5 of 13, by Sphere478

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need a full picture of your board. Unfortunately a manual doesn’t tell what you need to know.

Is this your EXACT board? Same chips? Heatsinks, configuration?
35-8258-00-5fbe31dbd08c5889140447.jpg

I see that it has two regulators. One on each side of the heatsink. But you say only one is installed? Therefore you likely only have a single plane voltage motherboard (can’t trust manuals 🤣) and should not be running a pentium mmx in it. You need a mmx overdrive. Or…
Re: Socket 5/7/SS7 (Voltage Interposer) Tweaker. (Beta)
This will be available soon.

The regulators on your board are linear, so likely even if you did have both there are no (easy) hidden settings. Getting a lower setting likely requires using a resistor jumper or changing a resistor or using multiple jumpers.

Being linear they will make a lot of heat. Especially on more advanced low voltage cpus.

As for the 233 mmx

Your 200 might support 3.5x most are locked though. But some are unlocked. Just try it, and find out

Higher fsb: we need a close up pic of your clock gen. So we can look up the datasheet.

Sphere's PCB projects.
-
Sphere’s socket 5/7 cpu collection.
-
SUCCESSFUL K6-2+ to K6-3+ Full Cache Enable Mod
-
Tyan S1564S to S1564D single to dual processor conversion (also s1563 and s1562)

Reply 6 of 13, by vintagely

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Sphere478 wrote on 2022-08-06, 17:27:
Is this your EXACT board? Same chips? Heatsinks, configuration? https://www.ultimateretro.net/motherboard/image/35-8258-00-5fbe […]
Show full quote

Is this your EXACT board? Same chips? Heatsinks, configuration?
35-8258-00-5fbe31dbd08c5889140447.jpg

It is VERY similar just a couple chips are kinda different (the BESTKEY one is in place of a VIA-II VT82C42N chip) and there are NKK chips near the EDO/FPM banks.


Sphere478 wrote on 2022-08-06, 17:27:

I see that it has two regulators. One on each side of the heatsink. But you say only one is installed?

In fact there are 2 on both sides. they are different, but 2 they are. Otherwise, the pentium MMX would be gone/failed long ago i guess

Sphere478 wrote on 2022-08-06, 17:27:

The regulators on your board are linear, so likely even if you did have both there are no (easy) hidden settings. Getting a lower setting likely requires using a resistor jumper or changing a resistor or using multiple jumpers.

That's bad news. How do you tell they are linear? Just to educate myself i'm totally n00b on this side.

Sphere478 wrote on 2022-08-06, 17:27:

Being linear they will make a lot of heat. Especially on more advanced low voltage cpus.

So basically a 400 mhz k6-2 will make regulators reach critical temp in like a minute of 100% usage?

Sphere478 wrote on 2022-08-06, 17:27:

Your 200 might support 3.5x most are locked though. But some are unlocked. Just try it, and find out

Is there a way to discriminate just by looking at the CPU? (serial number..) or i just have to set 1.5x and 66 mhz bus on the jumpers and see if that works? it's a black chip i heard they may be unlocked, or maybe not.

Sphere478 wrote on 2022-08-06, 17:27:

Higher fsb: we need a close up pic of your clock gen. So we can look up the datasheet.

Dunno where is the clockgen. Can you kindly help me locate it on the same picture you posted before?

Reply 7 of 13, by Repo Man11

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Here's a good video (for us non EE people) that explains the different regulators: https://www.youtube.com/watch?v=CMiGVQbMC5U

"A lot of times when you first start out on a project you think, This is never going to be finished. But then it is, and you think, Wow, it wasn't even worth it." - Jack Handey

Reply 8 of 13, by Repo Man11

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The Asus P55T2P4 had a version with single voltage, and one with split voltage. You can see the difference in the size of the heatsink on the VRM of the two different versions and the addition of copper chokes on the split voltage Rev. 3.1.

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"A lot of times when you first start out on a project you think, This is never going to be finished. But then it is, and you think, Wow, it wasn't even worth it." - Jack Handey

Reply 9 of 13, by Sphere478

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vintagely wrote on 2022-08-06, 18:22:
It is VERY similar just a couple chips are kinda different (the BESTKEY one is in place of a VIA-II VT82C42N chip) and there ar […]
Show full quote
Sphere478 wrote on 2022-08-06, 17:27:
Is this your EXACT board? Same chips? Heatsinks, configuration? https://www.ultimateretro.net/motherboard/image/35-8258-00-5fbe […]
Show full quote

Is this your EXACT board? Same chips? Heatsinks, configuration?
35-8258-00-5fbe31dbd08c5889140447.jpg

It is VERY similar just a couple chips are kinda different (the BESTKEY one is in place of a VIA-II VT82C42N chip) and there are NKK chips near the EDO/FPM banks.


Sphere478 wrote on 2022-08-06, 17:27:

I see that it has two regulators. One on each side of the heatsink. But you say only one is installed?

In fact there are 2 on both sides. they are different, but 2 they are. Otherwise, the pentium MMX would be gone/failed long ago i guess

Sphere478 wrote on 2022-08-06, 17:27:

The regulators on your board are linear, so likely even if you did have both there are no (easy) hidden settings. Getting a lower setting likely requires using a resistor jumper or changing a resistor or using multiple jumpers.

That's bad news. How do you tell they are linear? Just to educate myself i'm totally n00b on this side.

Sphere478 wrote on 2022-08-06, 17:27:

Being linear they will make a lot of heat. Especially on more advanced low voltage cpus.

So basically a 400 mhz k6-2 will make regulators reach critical temp in like a minute of 100% usage?

Sphere478 wrote on 2022-08-06, 17:27:

Your 200 might support 3.5x most are locked though. But some are unlocked. Just try it, and find out

Is there a way to discriminate just by looking at the CPU? (serial number..) or i just have to set 1.5x and 66 mhz bus on the jumpers and see if that works? it's a black chip i heard they may be unlocked, or maybe not.

Sphere478 wrote on 2022-08-06, 17:27:

Higher fsb: we need a close up pic of your clock gen. So we can look up the datasheet.

Dunno where is the clockgen. Can you kindly help me locate it on the same picture you posted before?

Okay, if there are two regulators and you have the jumpers for the voltages then it is probably a dual plane board.

This is the clock gen

069A8D5B-367F-4FF4-844D-F801B0AC9CB0.jpeg
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Just set 1.5x and see what happens. There are no markings to tell you, it is simply try and see.

I have a few 200 mmx chips that will do 3.5x but most of mine don’t.

You could try the cpu and find out 😀 but more current at less voltage means more heat. If it were mine I would probably risk it. But your call.

Btw, idk if you were trying to find the fastest chip for your board with what you got, but a k6-2+570 modded to 3+ is the best you can shoehorn in there. Also it’s a mobile chip. So if you can get down to say 2.0-2.2v it should be rather conservative on the wattage. And have more performance at 400 mhz. (If you are goin all in may as well fo all in)

Don’t try a + with more than 2.2v

If 2.5 is all you can get then a k6-3 non plus is your best chip.

That’s a lotta juice for those rega though. Try and see. If they are getting really hot then may wanna reconsider

Sphere's PCB projects.
-
Sphere’s socket 5/7 cpu collection.
-
SUCCESSFUL K6-2+ to K6-3+ Full Cache Enable Mod
-
Tyan S1564S to S1564D single to dual processor conversion (also s1563 and s1562)

Reply 10 of 13, by vintagely

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Sphere478 wrote on 2022-08-06, 17:27:

Btw, idk if you were trying to find the fastest chip for your board with what you got, but a k6-2+570 modded to 3+ is the best you can shoehorn in there. Also it’s a mobile chip. So if you can get down to say 2.0-2.2v it should be rather conservative on the wattage. And have more performance at 400 mhz. (If you are goin all in may as well fo all in).

Don’t try a + with more than 2.2v

Damn if i knew this before... anyhow i want to be sure to find an easy and secure way to reach low voltages on this board... before purchasing and then modding a cpu (which sound a tricky thing to do for a n00b like me). Also dunno if my BIOS (AMI) will like such a CPU or not POST at all. So better analyze the board first 😮)

The fact that i would be able to have integrated cache on the CPU makes me salivating since i will be able to cache another 64 MB of EDO (for a grand total of 128 MB) and overall a much faster system... being able to overclock to 75 mhz the bus would be nice too... since 66 mhz will bottleneck everything...

on the mobos manual a K6 appear on the jumper settings page (here page 6: https://www.ultimateretro.net/motherboa ... 40451.pdf ) so maybe there is hope...

Anyway the clockgen is on this photo here. it's a CY2260SC-3 9641 313100

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Reply 11 of 13, by Sphere478

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50-66mhz seems like

you can dig into the resistors on your fet jumpers and try to get them down to 2.2v

Or, my voltage interposer will be done soon.

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Sphere's PCB projects.
-
Sphere’s socket 5/7 cpu collection.
-
SUCCESSFUL K6-2+ to K6-3+ Full Cache Enable Mod
-
Tyan S1564S to S1564D single to dual processor conversion (also s1563 and s1562)

Reply 12 of 13, by vintagely

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Sphere478 wrote on 2022-08-06, 21:30:

50-66mhz seems like

you can dig into the resistors on your fet jumpers and try to get them down to 2.2v

Or, my voltage interposer will be done soon.

yeah i googled before your post and saw max clock is 66 mhz. Unlucky!

Any idea on K6-2+ modded bios incompatibility? guess it is a hit or miss...

you can dig into the resistors on your fet jumpers ( this one needs to be expanded a little sadly 😀 but only if you have really nothing else to do :p, or maybe link some place to improve my knowledge on what are talking about)

btw insane work for the k6-2+ mod, was just taking a look at the thread, really blew my mind 😁

Anyway man thanks a lot for the help, i will try the k6-2 and report back before the end of the next week i will be done with the testing.

Reply 13 of 13, by Sphere478

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The fet has a control chip and that control chip uses a resistance to decide what voltage to command. The voltage jumpers are linking to different resistors changing the value. So if you needed a different value to command a different voltage that isn’t a option it comes down to using multiple jumpers or a combination of resistors as jumpers or switching out the resistors on those jumpers.

A trim pot on a hard drive led pigtail comes to mind. 😀

Sphere's PCB projects.
-
Sphere’s socket 5/7 cpu collection.
-
SUCCESSFUL K6-2+ to K6-3+ Full Cache Enable Mod
-
Tyan S1564S to S1564D single to dual processor conversion (also s1563 and s1562)