Overclocking Q8200 Core 2 Quad

One of the big problems that faced a lot of motherboards featuring the Intel 3 series chipsets and NVidia 600/700 chipsets is that while they supported the Core 2 Quad processors, they weren't designed from the ground up to support them. Rather, support was patched in afterward. It is only the Intel 4 series motherboards that were fully designed to support them.

Unlike the current Core i3/i5/i7 microprocessors, the Core 2 Quad microprocessors are not native quad core microprocessors. Each Core 2 Quad is actually two Core 2 Duo microprocessors glued together via a multi-chip module.

From a signalling perspective there's very little difference between one Core 2 Quad in one socket, and two Core 2 Duos in two separate sockets. From an electrical perspective, a Core 2 Quad draws twice as much power as a similarly clocked Core 2 Duo.

As a result of Core 2 Quad doubling the current that the socket needed to provide, it was discovered that the VRMs on a lot of Intel 3 series motherboards and LGA 775 motherboards from other vendors were unable to handle the current demanded by the new quad core processors under overclocking conditions. Later generation LGA775 motherboards included more robust power delivery.

Another issue that crept up is that of FSB holes. These are far more common on the crummy NForce chipsets than on Intel chipsets, but they were still problematic. There are some clock and multiplier combinations which simply render the system unusable. The solution is to try other combinations which result in similar CPU/DRAM frequencies, but different FSB speeds.

For example, the Q6600 was designed around an FSB of 266Mhz (1066 MT/s, quad pumped). With a marketed speed of 2.4Ghz it was programmed at the factory with a maximum multiplier of 9x (266 x 9 = 2,394 Mhz). When paired with standard DDR2-800, a DRAM clock ratio of 3:2 was used (266Mhz FSB * (3/2) = 400Mhz DRAM IO bus). Many people found out that by changing the FSB clock from 266Mhz to 333 Mhz (1333 MT/s, which most 4 series chipsets were rated to handle) and changing the DRAM ratio to 4:3 (333 * (4/3) = 400Mhz DRAM IO bus) the CPU clock could be increased to 3Ghz without adversely affecting the finicky DDR2 controller. If the user wanted to take it further, they could increase the FSB to 400Mhz (1600 MT/s, only X48 chipsets were rated for this, but many were capable of it) and set the DRAM ratio to 1:1 which would result in a 3.2Ghz processor clock while retaining standard DDR2-800 speeds.

The difficulty with the Q8000 series microprocessors is that they were designed around an FSB of 333Mhz which means that it has a maximum multiplier of 7. If you are able to increase your FSB to 400Mhz and adjust your DRAM ratio appropriately you may be able to hit 2.8Ghz, a rather paltry improvement over 2.33Ghz.

Good luck.