I was wondering if anyone has actual experience running K6-2 400 CPUs at 2.5v core. I've read that 2.5 is the maximum suggested CPU core voltage for the K6-2 400 and that it can be run at this setting though overheating problems may occur. I ask because I have a FIC PT-2200 motherboard with the Intel 430HX chipset currently running a Pentium 233MMX, though the board is capable of recognizing a K6 up to 300, has 66mhz bus speed, and can be set to 2.5v core. (Being able to recognize a K6 CPU, a 66 bus speed, and 2.1 -2.5v core being the prerequisites for the K6-2 400, right?)

Someone might know but for the future this type of question would be better in the overclocking forum.

DerekW

This might be worth a read

I'm not one of those who think Bill Gates is the devil. I simply suspect that if Microsoft ever met up with the devil, it wouldn't need an interpreter.

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Don't waste your time man - the K6-2s (not K6-2+) are not overclock friendly at all. But if you don't mind cooking the CPU while you're at it, then by all means go ahead with your overvolting strategy.

You don't have much to lose, after all the CPU is worth less than a happy meal at Mickey Dees ;-)

The K6-2 interprets the 2x multiplier setting as 6x, so you could run a 400MHz CPU @ 400MHz (6 x 66Mhz) on your 430HX board. Your board probably only caches 64MB RAM though, so that's a bit of a performance deterrent. As for the 2.5v vcore...you're on your own. What is the default vcore for your CPU, 2.2v or 2.4v?

It has been a while but I found that the K-6 IIs were very overclock friendly.

"It has been a while but I found that the K-6 IIs were very overclock friendly."

You must have gotten a phenomenal CPU that was rebadged as a K6-2...........LOL. Overclocking was not a strong point for those CPUs. Oh, & BTW Doc. What would you consider as a very good overclock - 5%, 10%, 15%???

The FIC ftp site has some pieces of info about this model - it doesn't mention K6 cpu's at all, just K5s.
According to the AMD K6-2 Processor Data Sheet pdf here:
http://www.amd.com/us-en/Processors...

There are two K6-2 400 types - see the cpu markings

K62-400AFQ
- if marked 2.2v - 2.3v max recommended
- if marked 2.4v - 2.5v max recommended

K62-400AFR
- if marked 2.2v - 2.3v max recommended
- if marked 2.3v - 2.4v max recommended

Both will run at 66mhz or 100mhz bus speeds, but you need to have a K62-400AFQ with a marked core voltage of 2.4v to be able to use a 2.5v core voltage without burning out the cpu.
If that's not what you have, the cpu is likely to fry, even if overcooled.

If that's what you have, to have it run at 400mhz
set the Freq multipliers to X2 which will be interpreted by the cpu as X6
Freq 1 2-3, Freq 2 1-2
and set the bus to 66mhz
CLK1 ------------------ 1-2
CLK2 ------------------ 2-3
Core voltage / I/O voltage 2.5v, 3.3v
VR1 5-6, VR2 1-2

This mboard is not a good choice for using XP with.
It can take up to 160 mb of ram, but only if you can find and install 2-64mb SIMM modules - good luck finding those - and two 16mb SIMM modules - otherwise the max is 4-32mb modules - 128mb - half of the recommended 256mb XP needs to run as it should.
And as jam has pointed out, you have only 256kb L2 and any amount of ram of more than 64mb will not be cached and will run noticably slower overall.

Sabertooth:

K6-II 300MHz clocked to 400MHz = 33%

K6-II 400Mhz clocked to 500Mhz = 25%

MOBO Tyan S1590S.

I did not mess with voltage.

Doc,

Interesting.......care to elaborate on the multiplier deployed to achieve both of these overclocks, since (as claimed) you did not have to raise the voltage at all. Secondly were these the mobile or desktop variants of the K6-2?

Both were desktop AMD K-6 IIs. Vendor was JC SUN (I think).

On the Tyan MOBO 100MHz FSB is JP3, JP4, and JP5.

For 400MHz, JP8 off, JP9 on, JP10 on.

For 500MHz, JP8 on, JP9 off, JP10 on.

I had 100MHz RAM.

Sabertooth

PS

The 400MHz OC was an accident. I miss-jumpered the 300Mhz CPU for 400MHz. The 500MHz OC was on purpose.

PS

On the Tyan MOBO 100MHz FSB is JP3, JP4, and JP5 1-2.

My motherboard (FIC PT-2200) has 256 megs of EDO RAM installed (it can actually take up to 512). It uses the Intel 430HX chipset. It currently has a Pentium 233MMX installed but I was thinking about putting a K6-2 400 in there unless it's going to end up frying the motherboard. The closest I can set the core to is 2.5v, which I understand is the maximum suggested for the K6-2. The system has great cooling. Is that the only real issue, keeping the CPU cool?

There are two K6-2 400 types - see the cpu markings

K62-400AFQ
- if marked 2.2v - 2.3v max recommended
- if marked 2.4v - 2.5v max recommended

K62-400AFR
- if marked 2.2v - 2.3v max recommended
- if marked 2.3v - 2.4v max recommended

Thanks for this info BTW. I almost bought an FR.

"My motherboard (FIC PT-2200) has 256 megs of EDO RAM installed (it can actually take up to 512)."

I didn't think there there was any such thing as a 128mb SIMM module, and 64mb SIMMS are relatively rare, but I searched the web and apparently your mboard CAN take 128mb SIMM modules. First one I've seen that can.
At the time that mboard was made, 128mb SIMM modules would probably have cost more than $250 each, and 64mb modules more than $125 each - hence at the time few other than businesses could afford to install 64 or 128mb modules.

Sabertooth
Overclockabilty of these K6-2's seems to be very dependant on which chipset the mboard has, and what overclocked bus selections you have to choose from.
I was not able to get a K6-III 450 or K6-2 500 to overclock at all on my Epox MVP3-G5 (has the last Via MVP3 chipset) with standard core voltages, but I was able to overclock a K6-2+ 500 easily.
See Response 4 in this:
http://www.computing.net/cpus/wwwbo...

Tubesandwires:

Are you sure there is a K62-400AFQ 2.4v CPU? Of the many being sold online they are all 2.2v.

According to the AMD K6-2 Processor Data Sheet pdf (link in reponse 7) there were/are.

Also according to that, all the K6-2 400 cpus have an absolute max of 2.5v you can run them at. Any higher will burn out the cpu for sure, regardless of how well they are cooled. You would definately have to make sure you use a heatsink and fan with more than the usual cooling capacity - e.g. with a conventional heatsink at least 1 inch high. If you want to take the risk, go ahead and buy whatever you can get. You may be able to find more about what is required on overclocking web sites.

If you don't want to take the risk,
you could search the web for a used processor UPGRADE.
E.g. Evergreen made a "Spectra 400" upgrade. It is a cpu interface board that plugs into your Socket 5 or Socket 7 socket that modifies the core voltage to the proper 2.0, 2.2 or 2.4 volts, provides up to a 6X multiplier (of 66mhz), and came with, or the board can be used with up to, a K6-2 400 cpu, and it came with a CD full of bios updates for many older mboards in the event your bios can't recognize the K6-2 400 cpu (a program on the CD determines whether you need the update).
I used a Spectra 400 with a mboard with a 430 chipset and it worked fine. However, the Evergreen web site does not exist anymore, so if you get one it should come with the install instructions and preferably the CD, or I still have the instructions.

Powerleap made a similar upgrade kit, but it does not come with bios updates. In some cases the cpu will not work without one.

OR there are plenty of used Super Socket 7 mboards out there that are a better choice than this mboard, and most will handle faster K6-2s or can be more easily overclocked to as much as 600mhz or so.

I know there are easier ways of upgrading, that used motherboards capable of handling bigger CPUs like the K6-2 or K6-3 can be cheaply found, but I have a sentimental attachment to my current system and therefore was trying to see if I could just bump its performance up a bit. The PT-2200 motherboard I have was a premium board in its time (which is probably why it can even run 512 megs of RAM). It runs much more stable than the FIC VA-503+ that I have in another system and has niceties such as bios auto configuring installed drives. In short, it's a great board and a nice, stable little system and I'm wary of anything that might alter that. Maybe I just answered my own question though. The extra oomph of a K6-2 400 would be nice, though at this point I don't know if it would be worth it. I found an old web page on Google where a guy listed that his PT-2200 motherboard was running a K6-2 400, and that was what inspired me to get one. However, I've since come across conflicting information such as someone else telling me that the K62-400AFQ CPUs were defective, so I have no idea what to do. Basically, I'm back at square one, though maybe I should just scrap the idea at this point if a K6-2 upgrade is going to eventually leave me with a dead motherboard.

If you want a risk free upgrade, see if you can find a Spectra 400.

The original chomper core AMD K6-2 was overclockable, it was when AMD updated the K6-2 core to the chomper CXT core was when AMD K6-2s became non-overclockable.

I had the original chomper core and I got a 75mhz stable overclock from it from 350mhz to 425mhz with no problem. Later on I switched the chip and got 500mhz K6-2 that had the updated chomper CTX core version and that's when i ran into a problem overclocking it.

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