How many RAM modules do you have ? If you have more than one, you can try removing one, removing the other, switching to another slot to see if the problem comes from the slot.
Anyway if we go by elimination :
-It's not your GPU otherwise you wouldn't have an image.
-It's not your CPU otherwise the PC wouldn't start at all
-It's not your motherboard (or at least I don't think so) otherwise nothing would work
-It's not your HDD otherwise Windows wouldn't show up
Which leaves us with about RAM and that's it.