i will going to loop both cpu and gpu since i have to do one of them anyways; gpu more importantly, will one 240mm rad will be ok to run evga gtx580 and i3-2100 at the same time? and yes 580 will be overclocked but not too much.
Also, would i be able to fit XSPC X20 Dc-750 water/res combo in 350D?
since the i3 wont be a major heat source, a 240x 30 would be fine, but be warned that
if you do upgrade to overclocking "k-series" that small rad will not be acceptable for
any amount of cooling. you'll deffo have to get bigger/more radiators.
yes that bay res will fit the 350D, but the DDC or D5 would be a better part to consider
due to 2 water blocks. the 750 will work (for a short time) but will labor (and more likely
fail) where as the DDC and D5 are made for multi-block use.