Hello all, I have the following: * 2009 Mac Pro, 2 x X5570, 24GB RAM * GT120 All is great, boots up, works, all is fine - PCI fan at 700 rpm or so, PS fan at 500, totally quiet. I bought a 6870, put it in, all works, except PCI fan is now at 2000-2300-2500-2200-1900. If you ever cranked up that fan with smcfancontrol, you'll know that it's VERY ANNOYING to listen to at >1100 RPM. I suffered with this for a week trying over and over everything, reset SMC, reflash EFI, everything. Even did the netkas flash for 4,1 -> 5,1 MP firmware. Same thing, fluctuates between 1489 and 2500 rpm the PCI Expansion fan, and PS fan at 900-1500 all the time. Removing the 6870 and putting in the GT120 OR a GTX260 I had on site, immediately stops this problem and everything runs normally again at 600-700 rpm. Therefore it is perfectly obvious the card is causing this, but why? I have found since then a workaround, which is a bit silly, but it works. * Boot Mac Pro with 6870 * Listen to the extremely annoying PCI fan for a few moments * Start up "Open GL Extensions Viewer" * Run the "Open GL test" for about 20 seconds IMMEDIATELY after the test completes, the fan quiets down and operates EXACTLY as normal, with 600-700 rpm. Even if I fully utilize the machine after this "initialization", I'm talking about all 8 cores/16 HT running at 100% in FCP, still, PCI fan never goes over 700 rpm again. I discovered this by accident by reading some other guy's flames on another apple forum about the same behavior which started when he put a Quadro 4000 in his MP 09. Therefore, we know that since it happened to him with the Quadro, it's not an ATI 6870 problem, it's a MP issue. Anyone else have any comments or experiences with this one?