Rather than getting the H70 I would get any of these two:
1) NH-D14(Can someone tell me if his ram is compatable?)
2) Silverarrow (Same for the NH-D14)
If your ram isn't compatible then get yourself a Scythe Mugen 2 with a dual fan setup.
Edit: What is your ambient because I can get like 29/30 idle and 50/51 at 4ghz. try to put your FSB to 250 and up the clock while keeping the voltage to 1.4v in the bios. I can get 4ghz at 1.41v, fully prime stable.
he's got the ripjaws, which have these horrible protruding "saw teeth" at the top of them, that stick out a good distance above the module itself...its very difficult to mount a xigamatek darknight horzontal with them...and if that is difficult, looking at the picture of that cooler, i would say it would be even more difficult with that cooler.
i own a xiggy DK, its a great cooler, there are a few things that you can do, to increase its lifespan and usefulness, add a second fan, do a push/pull setup, switch to a higher quality thermal compound (like mx2 or that diamond dust one, and if you like it, artic silver 5), going vertical helps a bit, as now you can direct the air flow from the front of the case fans, to the rear case fans, instead of sucking up or pushing the hot air down onto the graphics card.
note: i'm not ashamed of how ghetto i am, i used twist ties from a box of trash bags to mount the second fan also, there are a few guides out there for different ways to improve heat transfer with the way you apply the thermal past, check those out as well