[FC5] Screen flickers under high load

[Seven of Nine]

This must be the most odd problem i've ever seen. Situation:
I'm running Fedora Core 5, on an Asus A7N8X-Deluxe with AMD Athlon 2800+ (barton). Inside is a nVidia Geforce FX 5600. The system is running Fedora Core 5. Hooked onto this PC is a monitor on DVI, and a TV on VGA. My X.org config is attached to this post. Installed are the latest official nVidia drivers, and all updates for Fedora are installed aswell. I'm not using AIGLX, just plain old X.org.
Now, when the computer is under high load for a period of time, the DVI monitor starts to stretch and destretch. Not so funny when participating in distributed.net, leaving the processor under constant high load. If I don't kill dnetc when the screen starts acting weird, it will start flickering (off for a while, then on again). Eventually the only thing that helps is killing the task that produces the load. The TV (VGA) remains to work correctly.
How comes, what can I do about this, and/or is this a bug in the drivers?

[Seven of Nine]

I am kinda sure that this really is a hardware/driver problem, as there appear to be no problems with the same screen on VNC. Who can help?

[jwlkr]

I have the same problem with an integrated Nvidia GEforce 6100. I think this has something to do with CPU switching frequencies ( I have an AMD 3500+). If I disable cpuspeed the flicker goes away. Let me know if you have clues as to why this happens.
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thanks
HP

PS: I have another computer with an AMD4800+ processor and an NVDIA 7 series diaplay card. I don't see this problem on that computer.