What you should do is to measure the HS that you're looking at and then cut out a square of cardboard that's the same size and then see if it clears the PSU. After you figure out if a larger one will fit, then do a search and see if anyone has asked the same question before you post a thread on it.
If you want to put a case fan on your HS, be advised that you won't get the same temps that you'd get if you used a fan that was specifically made for cooling HS's. It'll still work fine for cooling the HS, but it won't cool as well.
If you have any specific questions, feel free to PM me.. just click on my name and select "send a PM".
You have to check for whether the HS will fit in the case,though, especially if you have a micro-ATX case. Even some of the Lian-li ATX cases have trouble fitting the Thermalright HS's, so it's better to check before you buy. The mobo manu. will tell you if it'll fit your mobo without hitting any capacitors...etc.