I havea FX-53 so that is pretty lowend. I don't knwo waht stock sizes are but mien was about stock size, the CPU overheated understock conditions(w/o OC) in CS-Source full specs. I had plenty of fans and the tmeperature was pretty cool.
I bought a Tt Cooltower which is basically a gigantic copper heatpipe heatsink, now I never overheat and the highest temp I reacher was 61 degrees and it was under pretty harsh conditions.
If anyone is intrested I can sell you my old FX-53 heatsink for 3 dollars plus shipping, I was oging to post on the sale/trade but I don't have 40 posts yet.