im almost 500% positive you cant cool a 9800gx2 or gtx 295 with core only blocks (you can of course cool the 7950gx2 with core only but thats a totally different story)
full cover is the only way to go unless u figure out how to make a huge space for the cards similar to this http://www.swiftnets.com/products/7950gx2spacerkit.asp
full cover is the only way to go unless u figure out how to make a huge space for the cards similar to this http://www.swiftnets.com/products/7950gx2spacerkit.asp