Machine shuts down at 100% CPU

[eoin_ie]

This is a rather unusual problem and haven't seen a post about it anywhere before but hopefully someone can help me.

If my machine runs at 100% CPU usage for any length of time, it shuts down. My processor is an AMD Athlon XP 3000+ running at 2.1GHz. My motherboard is an Asus A7N8X-X and I have 512MB RAM. I'm running Windows 2000 Professional and Mandrake Linux. This problem occurs with both operating systems.

If, for example, I'm importing music from a CD into iTunes, my CPU usage goes to 100% +/- 5%, my screen shuts off first, and then my machine turns off. When I push the "on" button, it starts, doesn't POST and shuts down. If I push the "on" button again, it POSTs but my CPU speed is 1GHz. I can go into the BIOS and exit immediately and my CPU speed is back up to 2.1GHz. Same thing happens in Linux. If I'm running some code that takes up a lot of CPU time, the whole thing goes down.

For a while I thought it might be the CPU overheating but I downloaded the Asus Probe and it shows my CPU running at 50C +/- 10C. Someone suggested that my motherboard jumpers could be set incorrectly but I'm not sure if this is it or not.

Does anyone have any suggestions as to what could be causing this? It's really affecting my work as I can't run any proper programs.

[Tin]

It sounds to me that your issue is heat related. First off...software temp programs are usually off by a few degrees, sometimes much more. Have you removed all of the dust from inside of your case? The best temp monitors are the ones that use an actual thermal probe thats attached to the base of the CPU .

[Alfie]

You may want to check in bios and see what the default temps are for shutting down the computer.

[blue60007]

Also, what kind of power supply do you have? Also sounds like a bad power supply is being overloaded.

[kram 2.0]

I find that rather odd, as AMD Processors do not downclock the processors for overheat - especially the K7 generation. Before concluding on any judgement, will you post your full sys specs including the power supply unit? It does sound heat related - consider reattatching the heat sink/fan to the socket to make sure the contact between the two are firm. It takes a good deal of force to attatch the heat sink to the socket.

kram

[eoin_ie]

I've got a 350W power supply that came with the case (Q-tec). I re-checked the contact between the heatsink and processor today and added a thermal pad just in case. If anything it seems to have made it worse. Now the CPU speed won't go above 1050MHz no matter what I do. I spent about 5 hours this evening checking all the jumpers on my motherboard and configuring my BIOS to run with different settings.

Full spec list:
Asus A7N8X-X Mainboard
AMD Athlon XP3000+ 2.1 GHz
Corsair Value PC3200 512MB
Q-Tec Midi tower ATX 6024MD w/350W
Radeon 9600 PRO EZ 128MB AGP

[glc]

Qtec power supplies aren't the greatest. What are the Asus probe *voltage* readings?

[ktkendall]

when you added the thermal pad did you thoroughly clean the surface of the heatsink and the processor before adding the pad?? the fact it got worse tells me your problem is heat related and if you did clean the old pad or paste off good then perhaps you do not have heatsink seated properly. If it's just a bit uncentered or not level it will cause your symptoms.

[eoin_ie]

When I took off the HSF, the CPU chip had made an impression on the copper heatsink so it appears it was making good contact all the time. But maybe you're right: ever since I applied the thermal pad, it's been causing problems.

This morning I loaded Windows and ran Firefox - it shutdown after 45 seconds and wouldn't restart at all. It would power up but wouldn't POST at all. This is really scary because I need this machine for my course work and it's gotta be able to run at 100% for a good while - I'm running cryptanalysis programs.

[ktkendall]

I would probably start by reinstalling the heatsink fan. Use alcohol to thoroughly clean off the old pad, and reapply a dab of new paste after the surfaces are clean and dry, then carefully install heatsink fan checking carefully for alignment and proper seating..

[eoin_ie]

Alright, I'll give that a go so. It's taken me ages to even get the thermal pad so it'll probably be ages til I get some.

[ktkendall]

All you need is a dab of thermal paste, the thermal pad you installed is probably actually hindering heat transfer to the heatsink if you did not clean off the old stuff.

[eoin_ie]

Thing is, there was no "old stuff". When I was building it first, an "expert" told me I didn't need a thermal pad/paste. And I never had problems before with it shutting down. It's displaying another characteristic: the BIOS settings aren't being saved from power down to power up. They're reverting back to old settings and then, on startup, it says my CPU is running in safe mode speed and asks me to change the BIOS. I've tried resetting the CMOS bus that hasn't made a difference.

[ktkendall]

Yes you need thermal paste, and also sounds like you need a new cmos battery.

[blue60007]

Well that "expert" isn't very "expert" if they said you don't need any thermal interface material. Gotta have that.

If the CPU is running it safe mode, I think that might mean that it isn't totaly compatible with the BIOS version, you might have to do a BIOS update (but the shutting down problem needs to be solved first, you definitely don't want the computer restarting during the middle of a BIOS update).

[eoin_ie]

OK so I applied some thermal paste and the temperature has fallen. I'm still getting the "safe mode" speed error and when I do change it, it won't restart. I can exit from BIOS but it won't POST...

[Cricket]

Time to strip it down to the basics (motherboard, CPU, heatsink, video card, 1 stick of RAM, monitor, keyboard and power supply) and go from there. Follow the instructions in this troubleshooter. If you can POST in the basic setup, add one thing at a time until you can't POST.

Cricket

[eoin_ie]

OK solved. I think. And I hope.

As mentioned above, I applied some thermal paste. Then I updated my BIOS to version 1010. I also replaced my CMOS battery. I then manually specified my CPU Ext. Frequency and Multiplier to give me 2.1GHz (my original value).

It's been running for about 30 minutes now with Asus Probe registering the CPU temperature at 39C. I've also run a cryptanalysis program for 5 minutes causing 100% CPU usage and it didn't shutdown. MBM and Speedfan are both showing similar temperatures (they weren't before).

So it appears that it was a combination of overheating, faulty BIOS and incorrect settings. Anyway, it appears to be fixed now...for the time being. Thanks to everyone for your help, it's truly appreciated, couldn't have figured it out without everyone's help.

Eoin

[Khalil]

Originally Posted by eoin_ie Thing is, there was no "old stuff". When I was building it first, an "expert" told me I didn't need a thermal pad/paste. And I never had problems before with it shutting down. It's displaying another characteristic: the BIOS settings aren't being saved from power down to power up. They're reverting back to old settings and then, on startup, it says my CPU is running in safe mode speed and asks me to change the BIOS. I've tried resetting the CMOS bus that hasn't made a difference.

What kind of an Expert is that? Use good thermal paste it will make all the difference. I recommend Arctic Silver or Cermaique, make sure and go to their website and read up on how to do the proper cleaning prior to applying the stuff on.
http://www.arcticsilver.com