ATI Radeon 4870 insufficent power supply leads to permanent damage?

Hi,

I ran a Radeon 4870 on my Cooler Master 500W PSU, does that provide enough power for my graphics card? Because a few months after building my comp I have been getting a serious flickering screen problem that doesn't improve even after:

- upgrading PSU to Corsair CX600
- switching graphics card to Nvidia Geforce 9500 GT, using driver sweeper to remove old drivers
- switching monitors

I still get the flickering screen, especially when I play games or watch a movie.

Is my motherboard or CPU permanently damaged..??

THanks.

Thre rest of my specs:
CPU: Intel Quad Core 2 Q9400 2.66Ghz
Mother board: ASUS P5Q PRO (EPU) P45
Graphics Card: ATI Radeon HD 4870; then tested with Nvidia Geforce 9500 GT
RAM: Kingston 2x2GB DDR2 800
PSU: Coolermaster 500; then upgraded to Corsair CX600
HDD: WD SATA 750GB
Monitor: Dell 2209WA; then tested with a BenQ monitor