To overclock the board we changed from the OCZ 4GB kit of memory over to our tried and true Corsair 2GB DOMINATOR 10000C5D memory kit , which is rated up to 1200MHz at 5-5-5-18 timings. We’ve had this kit well over 1300MHz at CL5 timings, so it won’t limit our overclock.
To start things off we cranked up the CPU Voltage to 1.500V to see how fast we could get the Intel QX9650 on the 780i SLI. When we first reviewed this exact Intel Core 2 Quad QX9650 processor it was found to top out at around 4GHz on an Intel X38 motherboard.
The XFX nForce 780i SLI motherboard topped out at 4GHz also, but we were able to enable the half multiplier and got that additional 166.5MHz boost that we talked about in the BIOS section. It seems the half multipliers really do serve a purpose!
Now that the processor has been pushed to its limits at 1.5Vcore we wanted to see how high we could get the Front Side Bus on our 45nm Quad-Core processor. The 780i SLI motherboard was able to take our QX9650 all the way up to 475MHz FSB, which is a new record for this processor! The Corsair memory kit was running 1266MHz, so this confirms the board feature of 1200MHz memory! Memory bandwidth on Sandra XII SP1 was found to be 8434MB/Sec on the Int and 8390MB/Sec on the Floating point, which is great for the clock frequency. The 780i SLI motherboard had no problems running 1900MHz FSB with a 45nm quad-core processor, which is impressive. Now you have to wonder why NVIDIA doesn’t support 1600MHz FSB processors with this board.