cyclone3d wrote on 2026-06-20, 06:36:

Did you adjust the multiplier on the CPU by moving the soldered 0-ohm resistors? I see that the core shows K7750 (750Mhz), but CPU-Z is showing it as 800Mhz.

That's interesting isn't it? The number on the plastic case is AMD-A0800MPR24B which is an 800. I guess a factory overclock?

https://www.cpu-world.com/CPUs/K7/AMD-Athlon% … MPR24B%20A.html

After wasting an incredible amount of time, I finally discovered the underlying issue: this board doesn't support Thunderbird core CPUs which is what the 800 is. With all of my troubleshooting I sometimes wondered "Maybe this CPU has issues?" and wished that I had a second Slot A CPU I could try, but I was sure this was the only one I had. Then I discovered that I had another, a 650 MHz Pluto and once I installed it, all issues disappeared!

The Thunderbird will work with the original BIOS, though it will occasionally have a glitch. But with just the right settings, it will work correctly for many hours, completing Memtest86 and every benchmark you can throw at it. But if you should try a later BIOS with that CPU, it isn't at all happy. At some point I forgot that I had both of these, and grabbed the CPU that I thought I had gotten with this motherboard.

TL:DR the motherboard is fine with the most up to date BIOS as long as you are using a CPU the board actually supports!

It's nice to breath a sigh of relief when you've finally solved the issue. It's running great, no problems other than self inflicted ones from pushing it. After running it for a while, I thought I ought to repaste this 650 as I had done with the 800 Thunderbird. And like with the Thunderbird, it's nerve wracking because when you pop that plastic case off it really sounds as though you're breaking something! When I removed the heat sink, it had fresh thermal paste that looked to be something decent. It occurred to me that maybe someone had disassembled it and repasted it? Nah, but when I got it apart, sure enough the thermal paste was again fresh and appeared to be high end.

Even with a bit of overclocking it's about 1,000 points lower than it was with the 800 Thunderbird. The thing to do now would be to sell the 800 and pick up an 800 or 850 Pluto.