I just installed an X5650 (950-> L5639-> X5650) on a Gigabyte X58A-UD3-r v2, firmware FH, with 12GB RAM (6 x 2GB).
Running at 191 bclk for 22x (4.2 Ghz) on all cores and 23x on 1-2 cores (in Win7; OS X Mavericks only seems to give me all-core multis: 12x, 21x, 22x... odd).
VCore: 1.2125v (normal) with DVID +0.1 in BIOS -- highest reported in Win/OS X is 1.280 @ 22x all-core multi.
VTT: 1.295
Pll: 1.80
DRAM: 1.66 BIOS -- 1.63 OS
OS X 10.9.5 benches:
Geekbench 3 64 - 18,611
CB 11.5 - 10.75
CB 15 - 943
During Intel Burn Test (Win7) max core hits 65c, and during heavy photo/video in OS X Mavericks I haven't seen over 55c. This is with an old 212+ and MX-4 compound.
The chip progression- 950 to 5639 to 5650--- has been fantastic. Each chip OCs higher and runs cooler than the previous. My 950 was stable at 3.8Ghz all-core at 85C on IBT, 5639 at 3.8Ghz all core (18 x 210) at 65C IBT, and 5650 at 4.2Ghz (22 x 191) all-core at 65C IBT.
Knowing my board w/ same ram and L5639 can do 210 bclk, I think I could push this higher than the 191 I have now. But I'm just not that interested. I'm happy to be keeping the VCore and VTT below 1.3 in the OS and temps under 65C in those tests designed to push the thermals, while more like 50-55 under normal full-core utilization apps.
This thing eats FCPX and Aperture.