I saw a thread with similar problems to mine i.e. running certain games (in my case FIFA2000), after maybe 15mins the game will jump out to the Win98 desktop with no ill affects other than the game having stopped. This doesn't happen every time, maybe 50%, and doesn't seem to matter how long the pc has been running.
Cel II 633 at 100Mhz giving 950 Mhz; Iwill Slocket II and Global Win fan
128MB PC100 CAS2 SDRAM
ATI AIW 128
Previously, I've been running the same setup for 20 months with a Cel 300a o/ced to 450Mhz using 100Mhz bus and default volts with absolutely no problems.
I've only had the new CPU about a week.
I've run Sandra's burn-in tests for hours at a time with no problems.
I set up Quake 3 to run it's 2 demo's in a continuous loop for hours at a time with no problems.
The cpu temp. never gets up above 40 deg C. Normal running 30 deg or less. I have 2 extra fans - one sucking in air from the front and another almost in line with the CPU slot sucking air out at the back.
Couple of questions -
1] The CPU came with the core volts set to 1.9V ("guaranteed" o/c for 1 year) but I found that when doing a Reset (manually hitting the button or shutdown/restart) or booting back up when exiting the bios, it doesn't boot up.
Power off/on is OK. If I drop down to 1.75V then problem goes away and it's at this setting I've been running it at. Once in a while it may freeze while loading whatever it is loading after the desktop is up (works OK after 2nd try but I'm looking into this).
To cure the problem with the game, and maybe other things, it had been suggested to raise the voltage but this will bring the boot problem back (I tried at 1.8V). Will going above the original 1.9V help or hinder things? I'm just wondering if going down with the voltage is going the wrong way but I'm not sure how much I can raise it safely above 1.9V. I think CPU core for this cpu is 1.5 - 1.6 (?)
2] The CPU has a thermal pad. I hadn't seen this before on my old cpu.
Would removing it and placing the heatsink directly on the CPU be a good idea?
Presently, because the heatsink is lifted slightly off the outer surface of the cpu (because of the thermal pad?) I'm able to stick the temp sensor directly to the cpu. If I get rid of the pad where do you put the cpu sensor?
You may want to try HARD WIRING the CPU for 1.80v, this should solve your bootability issues. I can look up the chart if you need instructions. Also, I'm not sure your temp monitor is being honest with you-you actually have to have the sensor TOUCHING the edgge of the CPU core to get a good reading. You could try making where the edge of the core contacts the heatsink and putting it very close to the core by attaching it on the heatsink next to the mark. The rest of the CPU except for the core is PLASTIC and does not conduct heat well-you are probably overheating in your game, and running MUCH hotter than you think! I have found nothing short of the oversized PIII fan will cool the Coppermine at your speed!
Suicide is painless...........
I took the heatsink off and found the thermal pad was now stuck to it. When I first got the cpu and heatsink they hadn't been put together and the thermal pad was on the cpu core. And, yes, I had put my probe towards the edge of the plastic (stupid!). So I removed the thermal pad and used a thin layer of heatsink compound instead and placed the probe as close to the core as I could but still on the plastic. I'll try on the heatsink, as you suggested, later.
I decided to up the core voltage back up to the 1.9V setting that it came with to see what would happen. Temp is now maxing out at 50 deg C but I am also not getting any crashes! Also, the problem with not being able to soft-boot seems to have gone away.
Wonder if it was to do with the thermal pad being new and not sufficiently bedded in?
I don't really want to mess around with hard wiring yet so I'll give this a good burn-in and see what happens.
The Coppermine becomes unstable around 55C when overclocked. You can overcome that instability to some extent by using higher voltages, or better cooling. Your probably roasting right now, get a better cooler. I like the Volcano II by Thermaltake (NOT the ORB)! It is cheap.