55-63 degrees celcius is the rated maximum operating temperature for that processor, so up near 53 isn't ideal, but not in danger zone if that is under full load. Are you using the fan controller that came with that? You might have it stuck in "silent" mode, see if you can switch it to normal operating mode, or bypass it entirely. Or something might not be seated right
The other possibility is a bubble in the heat sync thermal compound. Seeing as you have built your own computer already i'm guessing thermal compound application is somethign you have done on several occasions, but just in case, and for others who might read this thread, a couple of pointers on re-applying thermal grease
1. Always clean the old CPU and the old heat sync thouroughly with rubbing alchohol and lint free cloth that you don't ever want to reuse. This step is messy, but critical. Just applying new thermal compound over the top of the old stuff can lead to air voids, or can actually end up insulating rather than conducting heat if you end up using a different type of compound (the silver based stuff and the ceramic based stuff can react funny sometimes for example)
2. Keep the new layer thin. You don't want to end up with too much compound. it's there to be an interface between the heat sync and the top of the CPU. To get a good bond, I like to pre-spread a very thin layer on the top of the cpu and the bottom of the heat sync, and then aply a tiny bit more in the middle where they will contact, pressure from the attaching mechanisms does the rest.
3. If you pull the CPU heatsync for any reason, it is best to start over, otherwise you risk air voids. I can tell you personally I am guilty of reusing compound sometimes, and sometimes it causes issues. Not a good habit to get into
4. Your thermal compound needs time to "set" and should drop at least a degree over the next day or two after you first bring up your PC
The other thing to look at would be what you are using for thermal grease. It used to be that Artic silver was the only game in town, and they are still good, however there are other, more efficient compounds available now. http://www.performance-pcs.com/catalog/index.php?main_page=product_info&cPath=46_58&products_id=28487
The Indigo Xtreme Thermal interface is about the coolest rated product on the market at the moment from the tests I have seen. I haven't picked one up myself yet, but it is on the list for next time I pull one of my personal CPU's. $20, they aren't cheap, but they tend to average about 5 degrees C cooler than artic silver acccording to most of the evaluations out there. Then again you sometimes have to take those with some skepticism.
Tons of other choices as well. Newegg also has them. http://www.performance-pcs.com/catalog/index.php?main_page=index&cPath=46_58&zenid=6a807a346039e96e95829cd97d9d2273
I tend to like Performance-pcs for my cooling and case modification toys as they have more of the top end gear than newegg does. Especially when it comes to fans and water cooling.
SO I dunno, hopefully that helps!