AMD 5x86 133mhz CPU question

Yes, another old computer/cpu/motherboard question, I know, but I shouldn’t have many more, or maybe even any more, after this one.

On a socket 3 CPU I’m toying around with, I have an AMD 5x86 133mhz p75 chip (33mhz * 4) which should run as fast, or faster, than a Pentium 75mhz (and if I set the bus speed to 40mhz then I’ll have 160mhz (40mhz * 4) which is equivalent to a Pentium 90mhz).

Anyway, when I boot, the boot up screen shows that the CPU is running at 100mhz. I have the motherboard jumpers set up right, so everything should be fine. I’m wondering if my BIOS can handle a 133mhz CPU, but I think it’s current enough. Maybe it’s nothing, and I’m still getting 133mhz performance, even though it’s registering at 100mhz. I tried Wintune 98 and it also said the CPU was 100mhz.
If anybody uses older computers, or remembers the days when they do, if you used a 5x86 chip, or something similar, did you get this problem? What would be a good benchmark program I could try to try and get the true speed that the CPU is running at? (I’m running Windows 98 if that makes a difference.)
Anyway, no big deal, but all help is appreciated, thanks.

Give this app a try…

I had a couple of 5x86 systems and I think you have to set the multiplier (as well as the bus speed) with motherboard jumpers on all those. I don’t remember a system with full BIOS control of these settings. Look for some motherboard jumpers.

If it’s showing up as 100Mhz it may be triple-clocked instead of 4x33Mhz. Not all socket 3 motherboards natively support AMD 5x86 processors, but there are tweaks available. AMD used to have a 5x86 motherboard compatibility list, but it’s not on their website anymore.

Check this site for info on workarounds. Seems complicated, but possible. Good luck.

Also check Qs 4 and 5 on AMD’s Am5x86 FAQ

If Wintune says 100, it’s running at 100. Do you know if it’s 333 or 425? If the BIOS can’t handle the CPU, it can be lying but Wintune should be able to tell.

To get clock quadrupling, you need to set it for what is 2x multiplier for an Intel CPU on the MB. See here.

Some MBs didn’t configure the cache settings rights. I had one MB where I had to jumper a cpu pin to fix that. (But it turned out to be unstable at 40Mhz bus: too fast for the chips driving the expansion slots.)

Running cachecheck can also be helpful.