Overclocking Intel's Core 2 Quad Q6600

XFX nForce 680i SLI Overclocking:

Our overclocking experiences with XFX’s nForce 680i SLI motherboard weren’t quite as fruitful as the experiences we had with the Asus P5K Deluxe, but that’s a trend we’ve seen in the past, especially with quad-core processors. However, the board's overclocking performance was hardly anything to really sniff at.

We didn’t encounter any problems with stability holes on XFX’s nForce 680i SLI motherboard, but we found that the board was very quick to become unstable.

For example, with the Asus P5K Deluxe, we could run just about every task except Prime 95 at 3400MHz, but the chip wasn’t fully stable until we got down to around 3350MHz.

With XFX’s nForce 680i SLI motherboard, we encountered stability issues when accessing the network at 3310MHz. It wasn’t until we dropped to around 3285MHz that we could run our full suite of benchmarks.


Full stability followed a lot sooner too, with the system successfully completing our eight-hour Prime 95 stress test at just shy of 3265MHz – this is 85MHz short of what we achieved on the P35-based Asus P5K Deluxe. In order to achieve this, we had to do quite a bit of tweaking to voltages in order to get the board stable – we’ve included some screenshots below to show what we changed.


The vCore Voltage was set to 1.4625V, but in actual fact the true value (at least, according to XFX’s BIOS) is lower than what we’ve set – this was also the case on Asus’ P5K Deluxe, so it’s nothing to really worry about. The XFX nForce 680i SLI mobo delivered a slightly higher voltage than the P5K Deluxe – all of 0.02V or 1.5 percent – but that shouldn’t affect things a great deal either.

As with the P5K Deluxe, just increasing the vCore Voltage wasn’t enough to give us a completely stable overclock with this CPU and we also had to tweak some of the other options for good measure. We tweaked the CPU FSB Voltage from 1.2V to 1.4V along with the nForce SPP and MCP voltages from 1.2V and 1.5V to 1.45V and 1.55V to help.