Can't overclock and old Cel566 to 850, strange prob

[ver1.000001]

When it comes to overclocking, my old computer ain't working right. I'm thinking it's either the motherboard or power supply but I'm not sure.

When overclocked to 850mhz, the core has to be raised to 1.75V. Anything higher and it has problems restarting. I can run CPU-stress software for a day without any errors or crashes, but I could just use windows for 20min and it would crash. Sometimes it crashes when browsing the web or opening a folder, or even playing MP3's. With MP3's it mostly crashes during the playback of a song, not at the start.

At 850mhz the CPU is 34*C idle, 42*C on load. I got Arctic silverII and a Golden Orb on it, aswell as proper case cooling.

The CPU will run perfect when the FSB is set to 75 or 83mhz at 1.5V. Problem is I can't have my PC running at those FSB's because with dual ram sticks windows won't start. I have 2 Micron identical 128mb PC133 sticks, and windows won't run at a FSB at 75/83mhz if they both are in there. Yeah it's strange, havn't found a fix yet.

Anyway, back on topic. I'm thinking it could be the power supply or motherboard problem. The Power Supply is a 250W and was origonally used in a PII300 machine. The motherboard is a ECS P6BAT-A+ w/ latest bios, and I wouldn't be suprised if it was it, that ram problem is just strange.

Now I'm not sure if this is the cause, but apparently I have an environment temperature of 40*C. That is in no way true, I assure you. Both MBM and the bios state ~40*C, but the environment temp cannot be higher than the CPU. My guess is the temperature sensor is beside a chip that is getting a little hot, problem is I'm not sure where the heck it is. The manual doesn't say where the temperature sensor is, how can I identify it on the motherboard? My guess is this chip is overheating and I need to cool it down when overclocking. It's not the VIA chipset, that runs pretty cool. So any ideas?

[Jon]

PSU could be a slight problem but the two biggest things I can see right off hand are your load temp which is too high for that chip and the voltage. A Coppermine Celly under full load shouldn't be going over 40C under load...it's just too hot, in most cases, for that chip. The core voltage is also quite low and I would say at least another 0.05V-.1V is going to be needed to make it stable.

[Tweaked!]

I would have to agree w/ Jon here, it sounds like your voltage and temps. My Celly 500 averages 35c under full load 24/7 folding. You need to raise the voltage slowly and check your heat sink to make sure you've got good contact, if theres any visible gouges, valleys, etc... you need to lap it with some good 800 grit wet/dry sandpaper to a nice almost mirror finish and reapply w/ the arctic silver. Make sure you don't use too much or get any on anything other than the top of the chip and hsf. Might even want to try lightly lapping the top of the chip (ever so lightly) and clean real good with rubbing alcohol (both components) before reinstalling. The ram should be able to handle your goal.

Btw, Welcome to the forums!:D :cool:

[ver1.000001]

Interesting, I thought it could handle ~40*C. Maybe I was just thinking of the P4's :D. If it's so temperature sensitive maybe that is why I cannot go over 1.75V. Well I can, but it won't post after a restart. Takes 2 restarts to get it to post over 1.75V. Anyway, thanks for the advice.

[Monaco]

welcome to the forums!

Personally, I think your temps are just fine. My C566 peaked at 47C, when heavily overclocked and overvolted. Your load temp is not too high at all. Lower would be better, of course, but 42 is not so bad. Try this- remove your case's side panel, and if your rig becomes more stable you know it was a heat problem after all :D

Sounds to me more like a mix of two problems- one being peripheral cards, one being a power supply.

Your system won't boot at 75/83 with two sticks of RAM? Try leaving in both sticks, but removing all your cards except video. If it works, you know the RAM is not the problem- it's an unhappy PCI card. If it does NOT work: could be a few things. Either a badly damaged or poorly designed memory controller in your motherboard (highly unlikely) or an incorrect BIOS setting.

For example, some boards let you run your RAM at +33 mhz over the FSB. Some BIOSes enable this automatically once your FSB passes 100. Some BIOSes, if you set +33 and then drop back to a 66mhz FSB, will set the RAM back to +33mhz again once you pass 100FSB (I.E. running at 66mhz with RAM @ +33 means at 100mhz, RAM is @ 133mhz! ) Some RAM will just not run that fast. Double check ALL your BIOS fields, make sure everything is set correctly. Turn your RAM, etc to it's slowest, least aggressive settings until you get this problem fixed. Yah, your RAM sure should get to 133 no problems, but hey, worth a shot! :D

Power supply- failure to boot on the first try is often the fault of a bad power supply. The fact that you cannot get more than 1.75 vcore points at your PSU also. Try raising your vcore to 1.8V or so, at default 566mhz. If it works at 566 but not 850, you need a better PSU.

It could of course be the fault of your motherboard. A whacked-out mobo can cause just about any problem known to man! Only way to troubleshoot that is to replace it, unfortunately.

Me bragging- I got my C566 to 850 at default voltage, 927 at 1.7V, and 995 at 1.92V- all the way stable. With a crappy FOP32, it never topped 47C. Sorry, just had to brag :D