Install all missing drivers first and fore most and see if that clears up your issues. If they don't:
Do the freezes happen randomly, or when doing certain things (for example when in games, watching videos or listening to music)?
Have you recently (apart from the power supply) changed any hardware?
Have you recently installed any new software?
What brand hard drive do you have? Use the specific manufacturer's tool rather than a generic one. Either look it up on their site, or post up who the manufacturer is, and I'll give you a link to the tool that you need. If it is Western Digital, the specific model is needed too, or at least the family.
When your computer freezes, do you ever get Blue Screen's, or does it just hang? If you get Blue Screens, follow
this guide
What you mentioned earlier about L1 cache by the way, that is normal, your processor has only 64KB of L1 cache. It may seem small, but it is like that on all processors, a Core i7 950 for instance has 256KB of L1 cache