I'm not sure where you can get that. excaliberpc.com probably has them. As far as the slk800 the A is probably easier to mount. It just sort of snaps onto your mobo. The U needs to be screwed into the mobo, but it's a lot more move friendly, if you go to lan's a lot. They are both very good, so you won't lose if you go with either A or U. If you want something a little cheaper than the 800 or 900 you might get the thermalright sk7. It's also a very good heatsink, for not as much money. I'd suggest getting a smartfan II as well to put on the heatsink.