I have been getting random BSOD's and general instability with P8Z77-V since I built it two months ago. It generally fails HCI MemTest, but it has passed once or twice when the PC was new. I have two identical sets of the Corsair memory, and they both fail, but I usually don't get the BSOD with just one 8GB set running. Today, with all 16GB enabled in BIOS, I got a BSOD on reboot 3 out of 4 times. However, it can go long periods of time with no visible problems even with demanding games and benchmarks.
The failures occur with any of the many variations in BIOS settings I have tried so far, including the Optimized Defaults setting. I'm not running any aftermarket firewall or anti-virus, just Microsoft Security Essentials. I have never had much confidence in the Asus Sonar DX. The drivers are dated from over a year ago, and many of the crashes involve a noisy audio crash. Another very similar system built with the Asus Sabertooth Z77 and an MSI 7870 has had only one crash, and that was before the build was fully configured. It has identical memory and is overclocked to 4.3 GHz. It also has the Xonar DX and all of the other components are identical or similar, like a 256 GB Crucial M4, and a TX750 PS.