FX5600/Twinview flicker problem
I've got a really annoying, intermittant flicker problem that I just can't solve. I run my box with a couple of Dell analogue TFT screens attached to my FX5600, and on the screen that's attached to the DVI out (with the VGA adaptor), I get a strange, quick yet very distracting flicker on the bottom half of the screen every few minutes. I tried swapping monitors - no difference, so it's definitely caused by the output. I recompiled my kernel to turn off all the APIC and ACPI functions, as mentioned in the driver README - no difference. I changed my window manager - nothing. I've hacked around with all manner of X config settings - nothing. I just can't make it stop and it's driving me mad. Downgrading the drivers to various older versions doesn't seem to make a bit of difference either.
The same thing happened with my previous card (an FX5200), which I sent back in the hope that it was just broken, but the same thing is happening with my new one and I just don't know what to do.. Google and all sorts of various forums I've searched in yield nothing. GL games work fine, and it doesn't seem to happen when running in console mode, weirdly..
Can anyone help?
Dell Optiplex GX270, 512mb RAM
Mandrake 9.1, Kernel 2.4.21-0.13 (custom compile)
XFree86 4.3.0, Fluxbox WM
2x Dell E171FPs running at 1280x1024/24bit/60hz (native mode)
Nvidia drivers 5336