Overclocking i7 930 on GA-X58A-UD3R and RAM issues

Hey guys,
Long-time lurker, first time poster...

Some details about my system:
GIGABYTE GA-X58A-UD3R
G.SKILL 12GB (6X2GB) DDR3 1600MHz
INTEL i7 930 2.8GHz
Corsair A50 CPU Cooler
Windows 7 64-bit

I messed around with the BIOS settings trying to overclock my CPU and I got it up to 3.5 GHz. With Realtemp, it measured 45o - 65o C under load. Is that safe with my cheap cooler?

Also, with it overclocked, Windows shows Installed RAM: 12 GB (8 GB usable)

Only when I load 'optimized' BIOS settings does it show 12 GB usable. How can I get it to use all 12 GB?

I'm not looking to overclock it too much (I don't have good enough cooling) but I would be happy with a stable 3.5 GHz using all 12 GB RAM. Any suggestions? Anyone have a similar setup?

Thanks!
rocko

My giga drops a stick too when the stix are running too fast, timeings too tight, or not enough voltage.

Bump QPI/VTT Voltage to 1.3-1.45V, IOH Core to 1.24V, and DRAM Voltage to whatever G.Skill recommends at DDR3-1600, up to ~1.7-1.72V w/ 12GB installed. You might also want to manually adjust each of the four primary DRAM timings to what the modules are rated at, for example 9-9-9-24 at 1.65V.