Get some EK or Koolance blocks. They're a little pricier but they mount effortlessly and will keep your VRMs relatively in check. I tried the XSPC blocks and I ended up throwing it on Ebay. The lack of standoffs made it really difficult to get a proper mount and there are plenty of stories of people killing their cards because of this.

I can't speak for the Swiftech FC blocks since I haven't used them.