I purchased a brand new 5670,installed it as instructed,but when I turn my PC on,there is no output on my screen.Ive checked all the cables,even replaced them,but it still wont work. I have a HP Pavilion a6125in.It came with some unknown PSU.On the inside it reads "HIPRO 250W"
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You might be pushing that PSU. Anyway, check the BIOS and see if you have to disable onboard video/set video to the pci-e slot.