Chkcpu wrote on 2024-04-29, 09:53:

Hi Axel, […]
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Skorbin wrote on 2023-06-09, 12:12:

And now, as I got hold of a FIC PA-2005 myself, I am so happy that this modified BIOS is available as well.
When the system is up and running, I will give you a feedback. Might take some time, though (still need to get and test some more components first).

Cheers, Axel

Hi Axel,

Earlier in this thread I indicated the limited Vcore support of the PA-2005 and the limited CPU support of the (patched) 6201J900 BIOS.
If you are going to mod the VRM or use an interposer to run a faster than 233MHz CPU, you will need additional BIOS support.
Let me know if you want this and I will put your request onto my "to be patched" list. 😉

Cheers, Jan

Hello Jan,

thank you very much for your offer!

The BIOS support for additional CPUs would be nice, but it is not urgent by any stretch of imagination.
The linear VRM on this board (as it currently is) limits the choice of CPUs anyhow.
And as I don't possess an interposer so far and not knowledgable enough to work on the VRM, I am fine with 233 MHz CPUs for the time being.
Anyhow, I don't mind if you put it onto your to-do-list somwhere in the future, as the wish to upgrade might arise and I am also not the only one to possess this board and others might enjoy the opportunity as well.

So feel free to do the patch, but take your own time!

Cheers, Axel

Whats the fastest cpu this board can take? I just got one and would like to put in fastest cpu it can handle.

Would it run k6-3 533mhz?

Omarkoman wrote on 2025-01-16, 10:30:

Whats the fastest cpu this board can take? I just got one and would like to put in fastest cpu it can handle.

Would it run k6-3 533mhz?

There's no such thing as a K6-3 533. K6-2 533 and K6-2+ 533 do exist.

The relevant things for running a CPU:
- support for correct voltate. K6-2 needs 2.2/2.3V, K6-3 AHX needs 2.4V, K6-2+ (or 3+) need 2.0V. Lowest documented voltage on PA-2005 is 2.5V. That is acceptable for K6-3 AHX, too high for K6-2 and deadly for K6-2+/3+ Possibly lower undocumented settings might be possible, but this is your biggest challenge. To get lower than 2.5V you need to mod the board (add a resistor) with which voltages down to 2V are possible. It looks like you can add the resistor over the voltage jumper, so it's a minimal (and reversible) mod.
- support for required FSB and multiplier. Fastest K6-3 is the K6-3 450, which is designed to run at 4.5x100. This board supports FSB up to 66MHz in A-revision and 75MHz in B revision, and can set multipliers from 1.5x-3.0x with remapping for 3.5x and 6x. With rev A, you can do 6x66MHz = 400MHz, with rev B you can do 6x75MHz=450MHz.
- BIOS must at least tolerate the CPU, preferably support it. Reading this post K6-2+/3+ won't boot due to BIOS limitations, but regular K6-2 would work unmodified. K6-3 is an open question. In general it behaves like a K6-2 in terms of support, so I would be optimistic.

TLDR:
- K6-2 won't work safely without modifying the board for lower voltage. If you do that, you can run it at max 6x75MHz=450MHz.
- K6-3 AHX might work unmodified at 6x75MHz, but no guarantees as no examples online (that I can easily find)
- K6-2+/3+ won't work unless you mod both hardware and BIOS

So, no guaranteed options but I'd personally give a K6-3 a try if I had this board and the CPUs.

Let's say you don't have/want that, what's the next fastest option?

Overclocking a Pentium MMX 233MHz to 3.5x75MHz=262MHz. Almost all Pentium MMX CPUs will be able to handle this overclock, they are some of the most overengineered CPUs ever made.

Note that at this point 'fastest' depends on the exact software you intend to run. Intel CPUs have - clock for clock - stronger FPUs (think: FPS in Quake), whereas Cyrix and AMD CPUs have faster ALUs (think: FPS in Doom, or desktop performance in Windows). A K6-3 at 450MHz with L3 cache will blow away any alternative for this board at anything, but once you've dropped below 300MHz, what is fastest can and will differ.

Just for the record: A Tillamook runs fine @ 4 x 75 MHz
You have to bridge pins 7-8 of "VR1" with a 390R resistor for 2V core voltage. This lets you use some AMD K6 and K6+, too. There´s a BIOS modded by Jan for this.

You sure about that BIOS? First thing I did was look at Jan's page but no sign of the PA-2005 here: http://www.steunebrink.info/k6plus.htm

thank you for the detailed reply, I will stick with current K6-200 in the board and find a proper super socket 7 board for faster CPUs and next gen games as they come with AGP slots as well.

majestyk wrote on 2025-01-16, 15:02:

Just for the record: A Tillamook runs fine @ 4 x 75 MHz
You have to bridge pins 7-8 of "VR1" with a 390R resistor for 2V core voltage. This lets you use some AMD K6 and K6+, too. There´s a BIOS modded by Jan for this.

dionb wrote on 2025-01-16, 21:06:

You sure about that BIOS? First thing I did was look at Jan's page but no sign of the PA-2005 here: http://www.steunebrink.info/k6plus.htm

Sorry majestyk, dionb is right. 😉
The patched PA-2005 BIOS I posted earlier in this thread only fixes the 32GB and 64GB Drive limit bugs. K6-2(+)/III(+) support hasn't been added (yet).

Cheers, Jan

Good you guys paid attention!
I mixed this up with some other FIC PA-wxyz model and was sure that you had added Write Allocation also.

Still it would be a good idea, because the PA-2005 is available in quantities at bargain prices all the time and the voltage mod is quite easy to do.