PCChips VX Pro+ Motherboard

[JET1]

I have a PCChips motherboard with a VXPro+ chipset. It has an AWARD BIOS version dated 7/4/97 and is an ultraDMA/33 board with a K5 100 processor. Can I upgrade the board to a K6-2 or only to a K6?

[Peter M]

Neither. That board, PC-Chips M537DMA33, runs at up to 75 MHz and 3.5x multiplier, and has no voltages below 2.5V.

This means your top candidate (among what is available in the shops now) is a Cyrix MII-333 "75 MHz bus 3.5x" at 2.9V. I've done exactly that upgrade recently (along with 160 MB of SDRAM), and that is stable and fast.

With the K6 series, your top choice is the K6/233 in its original 3.2V flavor - but the Cyrix at 263 MHz on 75 MHz bus is faster than that in almost any application.

You need the latest BIOS 1998/04/30 for this CPU, and for 64/128 MB DIMM support.

Regards, Peter

[Symes]

Peter,
As usual you are quite right as far as the standard specifications go, but there are plenty of people out there running faster processors!

Jet1,

The good news is that your board MIGHT be able to support a K6-2 or K6-3 (if you can get one!) upto 500MHZ !!!

All the details are on my website;

www.skinnedknuckles.co.uk (http://www.skinnedknuckles.co.uk)

[Peter M]

Hi Symes,

I knew you wouldn't remain seated :-)

Of course what I recommended is what one can do on this mainboard without modifying it in hardware.

Its voltage regulators can be tweaked to output 2.2V, and the latest BIOS release seems to boot OK with K6 family processors. Together with K6 doing 6.0x multiplier at the same jumper setting that means 2.0x to everyone else's processors, a modified M537DMA33 takes you up to a K6-2 or K6-III at 450 MHz (75 MHz 6.0x) ... unless the voltage regulators blow up at the 13 to 14 Amps that these thingies draw. My impression with the Cyrix MII-333 was that the latter's 8.5 Amps power draw was about what the board can feed.

Regards, Peter

[Symes]

As they say around here "like a dog with a bone!" :-))

I think you are quite right to state the 'standard' approach anyway - not everyone wants to start delving into their system and performing 'open heart surgery'!
And, just as with surgery there are risks - particularly with the more 'juicy' processors that the power regulation circuitry will not be able to cope, which in turn could lead to the *further* expense of a new board.

Still, gratifying to see that this old type of board can still get posts here at Sysopt!

Symes.

[Peter M]

... and it's particularly amusing how this supposedly "worst mainboard in the world" (as common opinion was back when it was new) lasts that long in so many homes :-)

Regards, Peter

[CocoPops]

Ok Guys,

I have a M537, and a TMC TI5-VGF board (see current thread in OC section) I have a K6-3 400, and I want to upgrade it to a K6-2 550, I would like to put the K6-3 400 straight into the M537 board instead of binning it, is it possible?? It is the 2.4v flavour so the min 2.5v of the M537 shouldn't be a problem right??

Lee.

[Peter M]

At 2.4V, the K6-III/400 requires that the CPU voltage regulators be able to feed 12.4 Ampères, with a regulation quality (deviation) under maximum load of +0.1V/-0.1V.

Problems arise if you set it to 2.5V - (1) you're already on the edge of the deviation bracket, with actual regulation surely going beyond the limits. (2) at 2.5V, the thing eats even more power, close to 13 Amps. (3) Heat dissipation will rise as well, with the 2.4V K6-III being hard enough to keep cool anyway.

I suspect you'll be able to anticipate what's going to happen to your M537's linear voltage regulators rated 5 Ampères ... and even if it's an M537DMA33 which has 10 Ampère switching regs, you'll be playing an unstable game.

Besides, you're going to notice that the improvement from replacing a K6-III/400 with a K6-2/550 isn't worth the effort anyway.

If you want to improve the M537 system's performance, see above.

Regards, Peter

[CocoPops]

Ok, makes sense.

So if I want to upgrade my K6-3 400, will there be any more Socket 7 chips?? Is there such a thing as a K6-2+?????

Surely, there must be some increase from a K6-3 400 to a K6-2 550 OC'd to 600??

Cheers,
Lee.

[Symes]

Cocopops,

I'm hoping that the K6-2+ will increase the upgradability too. But they're only going to be 'mobile processors' so I guess we'll have to wait and see if they're low voltage or surface mount or something else that'll stop us putting them in our S7 boards!

I have had one report of the 3x multiplier converting to 7x (like the 2x goes to 6x) but I've not had it confirmed. If it's true (and the AMD spec sheets don't mention anything above 6x) then we could be OK for a while.

*If* you decide to swap out your '400' for something faster don't bin it - I'm sure I could send a suitable drinking voucher your way in exchange!

Symes.