I was more than happy with my new GTX 285's performance until this morning when it refused to power my screen! It is just on 3 months old.

Replaced it with an NVIDIA GT 120 and was able to boot successfully. Hs anybody else had a similar experience?

I've had a similar problem.

First the mac would give me three flashes of the power light repeatedly when trying to boot up (which normally indicates RAM trouble).  After trying to boot three times, the machine simply wouldn't power up anymore until I replaced the 285 with my factory Geforce 120.

I tested the RAM with MemTest and everything checked out ok.   I took the machine to Apple, who replaced the logic board and power supply under my extended warranty, but the machine would still not power up as long as the 285 was inside.

I sent the 285 back to EVGA and received a new one in return.   It worked fine for 4 days.   Today, however, when i came in and tried to wake it from sleep all I get is three flashes of the power light, again.   repeating endlessly but not booting up.

This time I instantly replaced the 285 with the factory 120 and ran MemTest again, twice.  The RAM checks out fine.   So the RAM is fine, the Mac Pro has a new power supply and a new logic board and a new 285, and i'm having the same boot problem as before.

I'll try reseating it a few times like you did.    Weird.

I'm typing this message to you with the Geforce 120 card in the Mac Pro.  It works fine until I put the 285 in it.

-ed

I am sure you must have reseated your card a couple of times? Did you reset the PRAM and the SMC?

My problem has been resolved, for the time being!