|Intel DP67BG P67-Express Motherboard|
|Reviews - Featured Reviews: Motherboards|
|Written by David Ramsey|
|Monday, 03 January 2011|
Page 16 of 17
The Intel P67 Express chipset brings major changes to the overclocking process. Here are the bullet points:
Overclocking by raising the motherboard's base clock is now all but impossible. Of the three P67-based motherboards I tried to overclock, the highest increase to the 100MHz base clock that I could get to run through stress testing was...103MHz. The Intel DP67BG motherboard wasn't stable above 102MHz, and couldn't run above 101MHz in stress testing. This limited overclocking ability is apparently because the P67's base clock is used to derive almost every other clock in the system, including the SATA and USB clocks. While having a single clock be the base for every other clock in the system probably means cheaper, more reliable motherboards, it removes an overclocking mechanism enthusiasts have used for many years.
Intel compensates for this by giving all Sandy Bridge processors unlocked multipliers: K-series processors get "fully unlocked" multipliers with no limits, while non-K series processors are "limited unlocked" CPUs that can only have their multipliers increased by a maximum of 4. All Sandy Bridge processors have fully unlocked video cores, RAM multipliers, and power settings.
Overclocking Sandy Bridge CPUs is different in another way, too. While everyone has their own overclocking techniques, I generally like to disable "turbo" features and run all processor cores as fast as I can under stress by raising the base multiplier. Well, you can't do this with the Intel Core i7-2600K: in fact, you can't increase the base multiplier at all! This was true in both the Intel DP67BG motherboard and ASUS motherboards I used, so I suspect this limitation is built into either the processor or the P67 chipset. Your only option is to increase the multiplier that will be used by Turbo Boost, and you can set individual multipliers to be used when 1, 2, 3, or all 4 cores are in use. Thus, if you disable Turbo Boost technology, you can't overclock the processor at all.
This image shows the "Performance" tab of the Intel DP67BG BIOS. The "Maximum Non-Turbo Ratio" setting cannot be increased beyond the default of "34" (although it can be reduced); your only overclocking options are the multipliers used for the cores in Turbo Boost mode. One interesting thing here is that although the CPU's nominal TDP is 95 watts, it can use up to 120 watts for a "burst mode" of up to one second. This screen also allows you to up the processor voltage and disable V-droop, both of which I did for my overclocking experiments. With the Intel DP67BG motherboard, the best I was able to achieve was a base clock of 101Mhz with a four-core multiplier of 41, for a sustained 4.13GHz with all cores under load. Despite playing with higher voltages and the V-droop setting, increasing either the base clock or CPU multiplier by one would lead to crashes in stress testing. This low overclock is disappointing (the ASUS boards did much better), and probably due to the relatively immature BIOS. With further experimentation I probably could have tweaked the multipliers a little higher when fewer cores were running.
I did try Intel's Extreme Tuning Utility (XTU), which is supposed to provide an auto-tuning button on P67 platforms, but the version supplied did not display this button with this motherboard. XTU is very comprehensive, providing at least the level of detail that AMD's "Overdrive" does (and much more than ASUS' "Turbo V Evo" utility), but is apparently unable to apply any changes without forcing a reboot, so I found it more convenient to change settings in the BIOS.
Intel provides a Turbo Monitor utility to graphically display the state of the processor's multipliers.
The left image shows the processor in an idle, low-power state (as noted by the green leaf with the "Energy Saver" label). The right image shows the processor running in Turbo Boost mode, with the top of the dark blue area of the bar representing the stock 3.4Ghz frequency, and the lighter blue bar representing the Turbo Boost frequency. This is a fun utility but it would have been more interesting to show individual bars for each core.