Using the XMP profile, the suggested QPI voltage was 1.40V. But, in my case the memory controller wasn't happy until I gave it 1.45V. Once that issue was patched, the memory ran perfectly stable at stock, operating warm but not hot. The memory would tighten up some, but the CAS latency didn't like to go down to 8 over 1850 MHz, however, 8-9-8-27 was fully stable at 1805 MHz and 9-9-9-24 was stable at 2000 MHz. Overclocking was easy but my i7 920s IMC couldn't keep up, so I had to settle with 2105 MHz which required 1.5375V QPI.