I got a used video card for a Pentium 4 (socket 478)
system, and it keeps freezing. Looking for ideas.

-It’s an ATI Radeon X1650 PRO 512mb AGP
-Sometimes freezes during POST, sometimes freezes a couple minutes after loading XP successfully, sometimes won’t even display anything on powerup.
-Idle temp was 67 celsius before cleaning heatsink, fan, and cleaning and applying fresh thermal paste, 57 degrees after.
-Card is not overclocked.
-Two other AGP cards (Radeon 9000, and X1550) both work fine.
-PSU is 500 watts.
-1 optical drive, 2 hard drives, and 1 floppy drive are in use. I tried disconnecting *all* of these devices, and freeze still occurs.

I’m fresh out of ideas! Anybody have any?