4670 problem

Hi, sometimes when i play a game my monitor says it has no signal but i can still hear the game still running through the speakers.
I have a Sapphire Ultimate 4670 512mb, Thermaltake TR2 RX 500 PSU, Dell 2209wa monitor, 1tb hdd and 500gb hdd, 1 optical drive, 2gb ddr2 ram and athlon 64 x2 4200. I realize this isn't the most powerful system but should be more than enough for Age of empires 3 and The Sims 3(at least i hope)

I have just updated the ATI drivers to 9.6 tried with driver only and with full CCC but the problem remains unchanged.
My case is getting plenty of airflow and temps are good.
Using Windows XP 32bit sp3 genuine fully updated.

This has been happening for months and have not been able to fix it.

Does anyone have any ideas, any help would be appreciated

part of me is thinking this is a PSU problem but i don't want to spend money on one if it's not

Thank you for replying
i have just recently tried Sims 3 again this time in windowed mode at 1024x768 and it ran good for over an hour until it lost signal and i had to restart, would this imply it's a problem with the graphics card?

chek your vga temp maybe it's too high. i think ultimate is passive cooling version(i'm not sure) try to add a 90 mm fan on your vga heatsink

hi chris19992 was having the same problem as you with the monitor also had bsod lots of times i think i have solved my problem by underclocking the card with rivatuner 701.5 core and 922.5 memory been very stable for two weeks now and i've rekindled my love affair with cod4 hope it helps darren