Hi, i've just installed a new graphics card in my PC, a PCIe Radeon X800XT, now the computer wont boot, the fans come on for a split second and then everything goes off again... If I leave it for 10 or 15 seconds it will do the same at boot, but it wont do anything instantly after. I think the PSU might not be powerful enough for it as if I disconnect the power for the GC it will run but with "Connect Graphics card power cable" on the screen. The rest of the system is pretty greedy pwerwise too... AMD Athlon 64 X2 4200+, 1Gb RAM, 2 HDDs, DVD burner... The PSU is a 420W, thanx