Well you really want to keep it as low as you can, because more Vcore means more heat, so I wouldn't raise it unlit you need to. How are you testing it for stability? I use 3 programs for testing mine. OCCT, Intel burn test, and the every reliable Prime95. You should be able to run on all of these for at least a few hours. But you will need some sort of active cooling on your VRM.
The freezing during gaming may well be a CPU stability issue. It so, you should pick that up with one of the above test suites.
Motherboard: RIVE (3602 bios)
CPU: Intel 3930K @4646MHz
OS Drive: 2 X Samsung 840 PRO (Raid 0)
Storage Drive: 2 X 1.5TB WD Caviar Black RAID 0, 2 X 3TB WD Caviar Red, Kingston V100 256GB SSD
Memory: 64GB G.SKILL Ripjaws Z (F3-12800CL10Q2-64GBZL)
GPU: Gigabyte GeForce GTX580 @795MHz - 1536MB GDDR5
PSU: OCZ ZX1250
Cooling: Phantek PH-TC14PE
OS: Windows 7 Ultimate x64. (EUFI)