I've been running my ageing Core i7-920 C0 @ 3.8 GHz for some time now but it has never really been 100% stable on 19 x 200 BCLK with a VCore of 1.3 V, a CPU PLL of 1.88 V and a QPI/DRAM of 1.3 V. My memory is rated for 1,600 MHz @ 1.5 V. However, it was enough for most games so I just left it at that. Last week I started to get system freezes within a few minutes of booting into Windows after installing an Intel chipset driver update but they still occurred after I restored to the older drivers so I figures it was my CPU overclock that was unstable. This seemed confirmed when I dropped the timings down to 20 x 160 BLCK and everything worked great, including games, for four days without a single crash or freeze. I've just been experimenting with settings to get the 3.8 GHz stable and come to the conclusion that it is the 200 BCLK that is the issue as I can run the CPU at 21 x 181 BCLK or 20 x 190 BCLK and play games with no problems (I played Crysis 3 for two hours and left Unigine Valley running the Extreme HD benchmark last night for 45 minutes while watching the rugby with no issues). I was using these voltages though: 1.35 V for VCore, 1.96 V for CPU PLL, 1.35 V for QPI/DRAM, everything else was on Auto. So why can't I get 200 BCLK stable on my system? I've never been able to achieve 4 GHz with my CPU eitherr even 21 x 190 BCLK is not stable at the voltages in the paragraph above. Is there a BIOS setting I need to tweak manually to get BCLK stable. I'd prefer a 200 BCLK so I can run my memory at its rated 1,600 MHz speed. Should I just leave it 20 x 190 BCLK? Or is 19 x 181 BCLK better because it seems like lower BCLKs are more stable than higher ones (is that right)? Thanks in advance.