Here is a pic of my x1900gt next to my old x1600xt. Man its huge...a full 9". I ordered up some forged copper Swiftech ram sinks and a mammoth Thermalright vga sink for it. I thought I would post my OC' ventures for you all. Its for my PC workstation, but the same principles all apply to the mac card. Stuff should be here on Weds and Ill go from there.
By the way with stock cooling I have the gpu @ 625 (same as xt model) and memory@1440.
Okay, here is the heatsink removal and cooling upgrades. I used a cooler from Thermalright, Swiftech copper forged ram sinks, Lian Li 120mm fan, Artic Silver5 and Arctic Silver Epoxy. The ramsink came with aweful sticky tape which would not hold, so hence the epoxy. I havent started the benching or overclocking just yet, but I can tell you that the Thermalright dropped idle temps around 10 C. Not bad at all.
OC'ing complete, well at least with ATI catalyst control center. I was able to bury all of the controls to the highest points. >:D Temps were unreal too, with it never going above 51C. My x1950xt runs that same temp when at idle! Foldalicous!
Small update...card has been folding for 24 hours with a stable temp of 46 C. Wow, didnt expect it to be that low. I am trying out CoolerMasters new Viva Pro on a x1950xt and I will add that to this thread. I do have to say this about the Viva though, because of its design, three of the ram chips get no cooling at all. Hmmm, I can remedy that (stay tuned), but why should I have to?
Stock x1950xt OC w/stock cooler folding gpu temp 69 C. Not bad, but the Thermalright took close to 20 C off of the x1900gt OC! Better get another one. Room temp is 22 C. Update soon.