GT9800 (and previously a 8600 GTS) randomly hangs X, more frequently under load

[robsims]

The X server hangs randomly, more often under load but sometimes even during monitor blanking while the console is locked. I can usually, but not always, log in remotely. The log sometimes contains:

[ 6047.756] [mi] EQ overflowing. Additional events will be discarded until existing events are processed.
...
[ 6047.768] [mi] These backtraces from mieqEnqueue may point to a culprit higher up the stack.
[ 6047.768] [mi] mieq is *NOT* the cause. It is a victim.
[ 6048.048] (WW) NVIDIA(0): WAIT (2, 6, 0x8000, 0x0000a444, 0x0000ace8)
[ 6048.836] [mi] EQ overflow continuing. 100 events have been dropped.

but not always.

This issue has persisted from 32 bit to 64 bit switch, across a video card swap, and across multiple kernel and nvidia driver versions since approximately February.

[poltsy]

This started happening annoyingly frequently for me too when xserver 1.12 came out. Haven't seen a crash since going back to 1.10 from backports.