Dunga105 wrote on 2023-02-05, 14:22:

Hi, I’ve got a super socket 7 board that has a k6-2 500 in it. I’m wanting to downgrade to a Pentium 133 to make a 1995 spec mac […]
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Hi, I’ve got a super socket 7 board that has a k6-2 500 in it. I’m wanting to downgrade to a Pentium 133 to make a 1995 spec machine. I’ve swapped in the Pentium, and configured the jumpers for voltage (3.2v) bus speed (66 with 100 for memory) and ratio (x2). When I press the power button nothing happens. No fans, no hard drive noise at all. It’s completely dead. I swap the old cpu back in and reset the jumpers and it works fine.

I’m new to this era of PC building so I’m sure there could easily be something I’ve missed!

The motherboard is a jetway J 531 cf and the cpu is a Pentium A80502133 SY022 133MHz. The ram is 64mb of PC100.

Any advice would be greatly appreciated, even if it’s just pointing out the obvious.

Hello,
I wonder why you set 3.2V, a pentium 133 is a single voltage CPU.
But still fans (like a cpu fan) should always spin. Also when there is no CPU in there at all.
Can you confirm that? The fans spin with the 500MHz setting without the cpu being inserted at all.

So something must be very wrong with your jumper setting for the 133 chip.

Single voltage yes, but 3.2 / 3.3V is the correct voltage:
https://www.cpu-world.com/CPUs/Pentium/ ... -133).html

Have you tested the Pentium 133 processor in another system? Do you know if it's a working processor?

Some thoughts:

Some motherboards are happy when you set vcc2 to 3.3v (this is the only voltage you should attempt to set on vcc2 btw when installing a single plane cpu in a dual plane motherboard), unless you have control over vcc3 (some mobos do) you are basically paralleling vcc2 and vcc3 when you install a single plane cpu in a dual plane motherboard. Some vrms may be happy with being set at different voltages, some may not be. But there is a good chance the motherboard designers anticipated this scenario and it will at least not break it. But it’s best to have them at the same voltage none the less.

Some mobos have a p55/p54 jumper. Being ss7 it probably does not.

Sometimes it can be as simple as your cpu might be happier at a different bus factor. Try 1.5x and 2.5x if nothing else, as an experiment.

Finally, if all else fails, try a pentium mmx. You can set it to 133mhz. (Voltage 3.3vcc3 2.8vcc2)

Also try setting your ram multiplier to 1:1 and play with the agp/ram option jumper if you have one

Thanks so much for all your advice, I haven’t had a chance to try any of your suggestions yet but will post an update when I’ve found the time to have another go