A couple of weeks ago I got screen message " not set at optimum resolution" on screen on start up. Took out graphics card & OK. Yesteday put in new graphics card (thinking the old 1 was cooked) & got same message, took it out & still same message. Have now tested memory, new card & CPU in another computer & all work OK, put back in mine & still the same. Motherboard is a Foxconn mATX socket 939 all running at stock setting. Is it knackered?