I received my Thermalright Ultra 120 Extreme Heatsink today and note the following:
I checked how "flat" it was. I did this by placing a metal ruler on it's thin side on the base from corner to corner diagonally. While I couldn't get a decent picture of just how concave the unit is, I measured a 1.5mm curvature. Meaning there is a 1.5mm hump in it at the middle of the base.
If this is some sort of design feature, someone needs to re-design the base. I did a search on Google and found WAY TOO MANY references to people having to lap the crap out of the thing in order to get it to perform better than the stock heatsink. Nearly every single user I found who is having quality control problems are encountering the exact same ones;
o The Heatsink, as designed, built, and delivered, provides no increase in performance over stock (until lapped)
o The Heatsink base is curved, not flat
o The Heatsink base has more grooves than Soul Train
The base of the heatsink looks like it was machined by Stevie Wonder.
There exists an area the seemingly didn't get machined at all. The grooves in the heat sink are so pronounced that I considered boxing it back up immediately and returning it. I decided against returning it immediately in order to see if I could lap the heatsink to an acceptable degree.
I started the lapping process by using 800 Grit due to how badly convex and rough the surface was, and then moved to 1000 Grit, then 2000 Grit Wet-or-Dry Sand paper. I used a metal finishing sanding block in order to maintain the flatness of the base. After 2.5 hours of lapping, I had removed most of the nickel plating in the middle area of the heatsink and some of the defects in the base.
Nickle plating? It isn't worth a penny if you have to sand it off!
While most of the nickel plating is gone, the grooves remain. You can really see the "quality craftsmanship" on display here. (Close your eyes and imagine the Dakota Badlands)
I lapped the heatsink base until I could clearly see the writing on my camera in the reflection of the base, but after this exercise I ran into another problem when mounting it to the motherboard, but it's not one you would initially expect.
I use a FDI LanParty nF4 UT SLI DR Socket 939 board and the unit doesn't come with mounting brackets for a 939 board. When I placed my order I specifically ordered a Socket 939 mounting kit.
When I attempted to mount the heatsink the screws wouldn't fit into the mounting plate on the back side of the motherboard. I tried many different options such as using the springs from the mounting kit on the stock screws and all sorts of things like that but I couldn't get it to fit at all.
I then went to Thermalright's website and looked at their instructions. It calls for replacing the mounting plate that resides on the back side of the motherboard with a metal one if you are using a DFI motherboard. My problem is that I don't have one and one wasn't supplied in the Socket 939 mounting kit I ordered. Did I mention Thermalright doesn't make one?
Final result? I'm stuck with a piece of crap heatsink that
1. Is "supposedly" the best air-cooled heatsink on the market (that)
2. Doesn't sit flat even after lapping (and)
3. Has grooves the size of river gorges (and)
4. Won't fit my motherboard