Need a good low profile heatsink

I recently built a computer using an a8 3870k and an asus FA175 - M PRO.

I have a smallish cube style case that has good airflow from what I can tell. My gpu(runnin in dual graphics) is a HIS 6670HD and it seems to stay rather cool .

I have a 120mm exhaust fan behind the cpu and an exhaust fan that fits into a pci expansion slot(doesn't plug into MD).

The problem I have is that my temps consistently reach 60c under prime 95 after less than 15 minutes.

I have downvolted my vcore to 1.3V from 1.4V default but I just can't get the temps down.

I am looking to buy an aftermarket cooler but I only have about 90mm of headroom to be able to slide my MB tray past the power supply and into the case.

Any ideas?

I have tried reseating the heatsink, using a heatsink from an old phenom(slightly helpful), and removing the gpu(about 3c cooler without)

note: Asus AI suite gives me temps of around 62 while under full load, coretemp give me temps of about 54 under full load, but gives me idle temps of about 2c less than room temp while Asus AI suite gives me idle temps of about 45c.