Windows 8 is a bad choice for gaming.. Make sure you get gpu drivers from HP website and if they don't have windows 8 ones, then.. why did you even put on windows 8?
newer isn't always the best, some would argue with me here for sure, but I find windows 7 to be superior in every way, from performance to comfortability.
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Intel I7 3770K @ 4.5ghz, Cooler Master Hyper 212 Evo, Gigabyte Z77X-UD3H, Gigabyte HD7970 ghz edition, 4x4gb Kingston HyperX Beast 2133mhz, Seasonic Platinum 860, OCZ Vertex 4 128gb, WD Black 1TB, WD Green 3TB+1.5TB, ASUS Xonar Essence ST, ASUS VE278Q, Windows 3.11