Having just gone through this I thought I would share a few pointers and pics for people considering WC on their GTX 2xx cards.
First thing to consider is full block vs. dedicated GPU block and discretes for memory/power. In my case I chose dedicated GPU block for a couple of reasons:
1) Re-use when I inevitably upgrade. I don't have to drain my loop and reinstall. Plus $$$ investment in new full cover.
2) Flex issues. Some full cover blocks have had issues with flexing the board and causing some bowing over the GPU contact area. Since the dedicated GPU is only attached at 4 points very close to the GPU itself I am thinking there is no chance of this happening.
So once I decided dedicated GPU cooler I needed to think about the discrete cooling of the memory and power devices. I have tons of those little Zalman blue memory heatsinks but attaching lot's of these with new thermal tape is not much fun and until the tape sets they are prone to falling off when handling the card. Also, I have heard of overheating VRM's on the GTX2xx cards with discretes so something beefier should be considered.
That's when I saw these D-Tek Uni-sinks. They cover everything at once and they bolt securely to the card so no heatsinks dropping off.
Next I made the unfortunate assumption looking at the picture of the uni-sink that the rectangular opening for the GPU would support other types of waterblock. Bad idea. I ordered a Swiftch MCW60-R because of it's excellent performance data and discovered that the way that the uni-sink is built will only accept a D-Tek Fuzion GPU block. Unfortunately NCIX has a zero tolerance, no return policy on watercooling equipment even if it is still sealed in it's package
The next part of the puzzle is how the heck do you get the original heatsink cover off this thing? In the attached photo you will see the 10 screws that hold the front and back halves of the shell together. On my XFX card they were underneath the label so I chose to cut out the label in small circles to expose the screws. Peeling off the whole label would have been quite messy. Also, this back cover gets re-used with the unisink so keeping it clean looking is a bonus. Once you remove the 10 screws there are a variety of clips around the perimeter of teh shells that hold them together. Using a wide, sharp instrument (I used a chisel) you can leverage the parts apart in the area of the clips and they just pop open. I did it without damaging any clips but some people have reported breaking them. YMMV. To remove the top half you need to use a bit of a twisting motion combined with pulling it apart to loosen the TIM (Thermal Interface Material). Once apart clean it all up with IPA (India Pale Ale)... well actually IsoPropyl Alcohol but beer sounds good too
Fastening the Uni-sink is dead easy. About 10 screws and you are done. The Fuzion 2 water block then just fastens via 4 spring loaded screws to the unisink (don't forget the MX2 or your favourite TIM.
Attach it to your loop and start benching...
With my OEM heatsink and fan at 60% and Extra Voltage at 1.06V I was OC to 756 core and 1512 shaders and was hitting about 62-64C in Furmark.
With the Fuzion2 I was able to boost the extra voltage to 1.12 and increase shaders to 1620 and core to 810. Hitting about 43C in Furmark
Overall a highly recommended solution for your GTX 2xx card.