Graphics and quad core cpu problem?

Just been given a computer with an Asus P5Q Turbo motherboard, an Intel Q8200 quad CPU, and a single X1950 Crossfire graphics card inside. All BIOS settings are default. Sometimes when i boot up i get what can only be described as a frazzled effect picture on my screen until Windows takes over the bootup process, kind of like a badly fuzzy TV picture. It tiles four of them on the screen, so i'm thinking of perhaps a CPU/graphics problem. Sometimes it stays when Windows takes over the bootup, sometimes it doesn't. Sometimes she boots with no problem, other times it's back again. Motherboard and CPU are both new and never been overclocked. All other aspects of the computer runs as sweet as can be. Any Ideas anyone?