This is not a question, but advice to help system builders asking the same question that I was, and a follow-up to a previous thread I started (that I now can't find anywhere). I had purchased a Radeon 5970 along with my case of choice, to find that the card didn't actually fit in the case. Not even close. After some research and THG posts, I learned that there are actually a lot of cases that won't accommodate this card, and just a few that will. I got in touch with a dozen or so of the major case manufacturers to find out which cases will accommodate a 12"/300mm Radeon 5970 and will list my findings in the next post. I will list the name of each case, followed by a couple of links (one to the product page on the manufacturer site and another to a decent res image I can find in Google image search, if better than the one on the product page), and finally the price you can expect to pay in GBP. Sorry for the lack of USD, but it seems all Americans have to do is run a quick search on Newegg, so not that difficult :-)
This list is not exhaustive. Some manufacturers did not respond (yeah I'm looking at you, Thermaltake), but should provide you with a pretty decent selection of cases to choose from, across a range of price points. Some may also be discontinued... looks like Thermaltake maybe did receive the email, because their cases section has been rearranged, quite a few moved to the Discontinued section (including the Eureka).
Reason there are so many Silverstone cases is that they were helpful enough to send me a spreadsheet including most (not all) of their cases with what size cards will fit by default, what needs to be moved or removed to make more space (where applicable), and how much space you'll have to play with when that is removed. If you'd like a copy of the .xls, feel free to PM me (or you could just email Silverstone).
For anyone new to building computers (and to THG, Anandtech etc), the Antec 900, 902 and 1200, as well as the Coolermaster HAF 922 and HAF 932 are very highly regarded.
Special thanks to those who helped me out in that original thread (wherever it is), especially to THG bearded guy. Can't remember your username, but the case fits the card like a glove and looks awesome :-D Nice one mate.
nice post but it is only good for people who can actually AFORD to buy a 5970 not just all the people who want it. lol
If you only want a 5970 and won't actually buy one, you don't need this list anyway :-) You can buy pretty much any case you want with smaller cards! Far as I know, other than the 5970 at 12", only other card currently out there above 10.5" is the 5870 at 11". I can also post a few more Silverstone models for additional options that will accommodate a 5870, but not a 5970.