Regarding the Switch 810 bottom 240 mount. It is true that you can not attach all your normal 8 screws, but you can attach two in the middle if you slide the rad to the left 15mm. You could drill holes to attach more if you wanted, but two is really plenty for holding the rad in place. Top mounted you can attached all 8 screws, but I think you'll generally get a degree or so better performance using bottom mount vs top.
This picture shows the general layout. The two holes holding the right fan in the middle will line up with the case holes:
The above was an attempt at trying pull, but push withfans on bottom is my preference as it seems to again yield just a hair better pefromance in trials testing.
So...it is "doable", no... not perfect for all 8 factory holes, but a 240 can certainly can fit down there and the tubes are just long enough on the H220 and if you remove the dust filter plenty of good cold ambient air flow. More importantly it will leave you with room to add a 360 rad up top later if you want.
I've played around with a lot of rad mounting options, and this bottom location is the best so far in terms of absolute performance and max noise reduction. The H220 will fit down there with two screws using the factory screws holes, or you can drill a few more if you want more...not a big deal. I was pretty happy just using two myself. Put a little foam tape on the fan corners to help decouple the rad/fans from the case, add a rubber washer to the two mounting screws and you can really make a nice vibration free mount that way. Just like pumps, sometimes more mounting screws will only transfer vibration noises more, why increase noise when you don't have to..my 2cEdited by Martinm210 - 3/9/13 at 4:49pm