got Xid errors and got rid of them...
I upgraded to from 1GB RAM to 2GB RAM on my x86_64 box running FC x86_64/kernel-2.6.15/1.0-8178 drivers.
Because the new ram was better I overlocked my cpu (which was overclocked before) from 2610Mhz to 2691Mhz.
I started glxgears to see how the fps changed... but glxgears showed 10300fps (instead of 6800-7000 before) but it did not draw anything.. so I strated doom3 timedemo and got 30fps (was ~55-62 before). the I started ut2004 and it crashed. looked at dmesg and found the Xid errors. Thought it was related to the 2GB Ram so I booted with mem=1024M but the problem still was there..
so I clocked down the cpu to 2655Mhz and they where gone.
Thats lets me assume that the Xid errors are because of instable cpu/mobo/ram combos.
Can somebody who gets the Xid erros try any stress testing app like prime95 (linux version exists) to see if this is true? (or try to downclock his/her cpu)