they are usually 6-32 threads.
Just go to a hardware store with the rad and fan and ask some one to point you to the 6-32 thread machine screws. They should have a ton of different lengths and then find one that works for you.
A forum community dedicated to overclocking enthusiasts and testing the limits of computing. Come join the discussion about computing, builds, collections, displays, models, styles, scales, specifications, reviews, accessories, classifieds, and more!