Help Solving This Freezing Mystery

I've got a computer that keeps freezing. I've replaced the harddrive, run all the ram through memtest for about 20 hours, replaced the GPU, tried a different power supply, and replaced the thermal paste that connects the CPU with the heatsink. Nothing is overclocked. I've got enough fans.

I just can't figure out what needs to be done. The only things left to be replaced are the mother board and the CPU. Can anyone tell me of a way to test these and make sure they work?

Is there something I could be missing in terms of some other messed element that could be causing the freezing?

Thanks for your time.

Motherboard: MSI k8n Neo4 Platinum
AMD 64 3200 Athlon 64 939 PRT
Corsair 2x1 gig DDR 400 Ram
OCZ 520 W power supply

 

replacement is the only way to test them I'm afraid

 

I don't know that I would take a stab at the issue with the general info you've supplied. You haven't said much about what it's actually doing. Some folks system freezes when they boot and they never make it past the Bios. Others freeze once their in the OS and other's freeze online. Software as well as hardware can cause a system to freeze. And peripherals, modems , routers, etc. Can you share the how's and what's with us? Let us know...Jazz

 

The computer freezes while It's in the OS (currently, ubuntu is installed, but the same thing was happening with Windows XP, so I"m fairly sure it's not software). Also, after it freezes, sometimes the computer will not immediately reboot,but has to wait awhile. Sometimes, but not always, the error message given is:

"Error 18 : selected cylinder exceeds maximum supported bv bios."

If I leave it for a few hours, the computer will often reboot, though.


In terms of internet, I have a Motorola cable modem going through a wired neatgear router. Another computer on the connection does not freeze, so I have a feeling that this is not it. In terms of what I'm doing, my computer is always connected to the internet while on, but I've had it freeze while I was browsing as well as when I'm typing in a text editor.

Any ideas? Need more info?

 

Usually the pause before restarting is in the power supply, but the only thing left is the motherboard as I see you tried another one. Was the other psu sufficient quality to rule our psu though?

 

Well the Error Code you've shared sounds like you've got a bios issue with a HD? Have you upgraded your bios? The Code itself is relative to Linux in most instances. Jazz