Graphics card (and maybe PC) problem...

Hello,

A few days ago I was getting the blue-screen-of-death quite regularly.

Upon opening my case the graphics card (Radeon 4890) felt incredibly hot (not sure how hot they're supposed to get). So, I took it out and blasted it with compressed air, got all the dust off it etc etc.

Now, my computer will not boot up at all, and the 4890 had 3 flashing lights on it:

D1601 - Red LED On, shows critical temperature fault

D1602 - Red LED On, shows External power connector A was removed

D1603 - Red LED On, shows External power connector B was removed

The card would start up, pause, lights would come on, then re-start ad infinitum.

It's as if the card wasn't getting any power, however I've checked the power leads many times (I'm no expert however)

I also tried a different card which wasn't powered by PCI-E, and had the same results (card would boot up, pause, then restart...)

I'm now at a loss as to what it could be!

PC specs:

Corsair Hydro H60 High Performance Liquid CPU Cooler

Corsair Vengeance Blue 8GB (2x4GB) DDR3 PC3-12800C9 1600MHz Dual Channel Kit

AMD Phenom II X4 Quad Core 955 Black Edition "125W Edition" 3.20GHz

XFX ATI Radeon HD 4890 1024MB GDDR5 PCI-Express Graphics Card

Gigabyte GA-MA790XT-UD4P (Socket AM3) PCI-Express DDR3 Motherboard

PC Power & Cooling Silencer 750 Quad-Crossfire 750W

Any help would be greatly appreciated