Playin' w/ an old Pentium

Johan · Jan 16, 2002

I have an old Pentium 100 machine laying around for which I received a 233MMX CPU. I don't know the mfg. of the mobo (no mfg. markings on the mobo) but it has a 430FX chipset.

Anyway, I crammed the 233 into the old faithful socket7, set the jumpers on RSVD for the multiplier (2.5x was the highest written value) and 66MHz for the FSB. It booted up fine and runs at 200 (according to WCPUID). I'd like to get a little more out of it if possible.

There is a RSVD jumper position under the FSB section. What would this correspond to? A higher FSB?

I tried SoftFSB but, since I don't know the mobo (unfortunately, the proggie doesn't list old P1 mobos) + I have no idea what the PLL is, I didn't have any luck.

Any ideas and/or thoughts. I realize that this may seem a ridiculous exercise to some but I'm enjoying the learning experience.

The Doors · Jan 16, 2002

Hi Johan, welcome to the Forum,
I don't know about the reserved jumper, but to know about your Mobo & PLL try to use Sisoft Sandra, and take a look into the Mainboard Information module for the model of System Clock Generator.

I hope it helps you

eobard · Jan 16, 2002

Johan said:
I have an old Pentium 100 machine laying around for which I received a 233MMX CPU. I don't know the mfg. of the mobo (no mfg. markings on the mobo) but it has a 430FX chipset.

Anyway, I crammed the 233 into the old faithful socket7, set the jumpers on RSVD for the multiplier (2.5x was the highest written value) and 66MHz for the FSB. It booted up fine and runs at 200 (according to WCPUID). I'd like to get a little more out of it if possible.

There is a RSVD jumper position under the FSB section. What would this correspond to? A higher FSB?

I tried SoftFSB but, since I don't know the mobo (unfortunately, the proggie doesn't list old P1 mobos) + I have no idea what the PLL is, I didn't have any luck.

Any ideas and/or thoughts. I realize that this may seem a ridiculous exercise to some but I'm enjoying the learning experience.

Max 2.5 multiple and 66fsb sounds like it's a socket 5 board, not 7. Have you lowered the core voltage to match the new cpu???

Flu!d · Jan 16, 2002

If he's using an MMX processor it pretty much has to be at least Socket 7 due to the split vio and vcore voltage level requirements of the MMX processors....

Johan · Jan 16, 2002

Thanx for the kind welcome.

I tried the reserved jumper setting for the clock settings and it didn't like it. It didn't detect my kb or mouse, didn't want to go into BIOS and took forever to post. That seems like a dead end.

The only jumper set remaining has VRE and STD written by it. I assume this is for a voltage setting; not sure which it should be at. It is currently on VRE and runs fine (slow, but fine).

I am going to DL and install Sandra so I can get some more info...thanx.

eobard · Jan 16, 2002

Johan said:
Thanx for the kind welcome.

I tried the reserved jumper setting for the clock settings and it didn't like it. It didn't detect my kb or mouse, didn't want to go into BIOS and took forever to post. That seems like a dead end.

The only jumper set remaining has VRE and STD written by it. I assume this is for a voltage setting; not sure which it should be at. It is currently on VRE and runs fine (slow, but fine).

I am going to DL and install Sandra so I can get some more info...thanx.

According to the manual for my socket 5 motherboard VRE is 3.5v and STD is 3.3v. A Pentium 233MMX needs 2.8v core so I think you'll get more life out of that chip if you run it with the STD setting. Of course you should double check that with your manual before making changes.

As for the board having to be socket 7, my socket 5 board will run Pentium MMX chips IF a voltage regulator is installed.

batboy · Jan 16, 2002

You said that the highest FSB was 66 MHz and the highest multiplier was 2.5X. But, then you said the CPU was running at 200 MHz. Something is not right, because 2.5X66=166 MHz not 200 like was stated.

nil_esh · Jan 16, 2002

I have a 430HX mobo and all I can get out of mine is 3 * 66 (200). Sounds like its the same for your mobo, and that's probably all you're going to get out of it.

But you can keep trying.. Try all the multipliers (even the lower ones) and see what happens. There are some CPUs that interpret the lowest multiplier on the mobo as the highest actual multiplier (e.g. K6-2+ and K6-3+).

eobard · Jan 16, 2002

nil_esh said:
Try all the multipliers (even the lower ones) and see what happens. There are some CPUs that interpret the lowest multiplier on the mobo as the highest actual multiplier (e.g. K6-2+ and K6-3+).

K5's do that too, they translate 1.5 into 3.5 but I think all pentium 1's take what you give them. There is a mod to gain extra multipliers, you just solder a wire (or jumper block) to two pins on the underside of the motherboard where the cpu socket is. I've seen the site but can't find it now. If I stumble across it I'll post the link.

Johan · Jan 16, 2002

You said that the highest FSB was 66 MHz and the highest multiplier was 2.5X. But, then you said the CPU was running at 200 MHz. Something is not right, because 2.5X66=166 MHz not 200 like was stated.

There is a RSVD jumper setting and this is where I'm running the mobo; the RSVD clock setting gives me 200 MHz. At the 2.5x setting, the CPU is @ 166 as expected.

Eobard, I'd be very interested in that link if you run across it. The board is a socket 7 (it's labelled as such) but Sandra is not giving me any useful info. Gonna try Motherboard Monitor to see if I can get a reading on the Vcore; no documentation so I'm playing a bit of a guessing game.

Thanx for the info guys.

Johan · Jan 17, 2002

No luck for obtaining Vcore w/ MBM5

TimG · Jan 18, 2002

Some Winchip 2s had a 4x multiplier mapped to the standard 2x one, so would let you get 266 out of a board that only had a 3x mult. Hard to find these days, though...

calypso_ri · Jan 21, 2002

430FX chipset doesn't support P55C CPUs... What I wanted to say, 430FX chipset doesn't support MMX CPU at all, it doesn't have the right voltage for these CPUs... You are running it at 3.3V instead of 2.8V for core + 3.3V for I/O! You should better get yourself a very good cooler, or you might really fry this 233MMX you are using!

And, I hardly believe that FX board supports >3X multiplier...

And, again, there is something called degenerative overclocking... It means that you try to degenerate your board, find what is connected to what, find the PLL, find the crystal and replace it with a faster one plus making all the arrangements...

I do not recommend this at all! If you don't know what are you doing, you could fry your board, and all the I/O on your computer, so, stay at these 200MHz, or get yourself a newer board (VIA MVP3 chipset maybe, or SIS TXPro)...

calypso_ri · Jan 21, 2002

I forgot to mention...

Look at the mainboard and find one shiny little metal cap, look at it and there should be something written on it... Something with the numbers 14.318, org 14... It's the quartz crystal, and PLL chip uses him to make all the frequencies on your computer...

Now, near this crystal thee is one chip about 2x1cm, with 24 little (how to say it in english) legs? You know what I ment... Now, this is the PLL chip, look at it, write the data on a paper, and try SoftFSB now... If it works, fine, but I really believe that it couldn't work, because old PLLs weren't programmable...

(

Greetings from Croatia...

P.S. Do not try VRE voltage on this CPU! VRE voltage is 3.45V, which is more that STD (3.3V)!!!

Johan · Jan 22, 2002

Thanx for the advice.

I am leaving the chip running at 200. Voltage is on the STD setting so, like you said, it is getting too many volts since the mobo is not designed for the MMX chip. Luckily, there is sufficient cooling and the heatsink doesn't get too hot to the touch.

I'll see how long the chip lasts; not a big deal if it fries. Learned quite a bit though....thanx.

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