As I mentioned, I would be thrilled to get more juice out of my CPU (Intel Q6600, a Core 2 Quad), but I’m not going to do it at the expense of causing my system to crash, overheat or otherwise become unstable.
A lot of my reading led me to believe that by changing only my motherboard’s FSB (front side bus) speed, I could get more performance without needing to tweak other values.
So in my ASUS P5E’s BIOS, I went to the Extreme Tweaker menu. The standard value for practically everything is “Auto”. I changed AI Overclock Tuner to Manual, which exposes the FSB Frequency option. The current value of the FSB was 266 MHz. The standard multiplier value for my Q6600 Intel Core 2 Quad CPU is 9X, so the effective CPU speed was 2.4 GHz. I changed the FSB value to 300 (which would take me to 2.7 GHz), and then restarted.
In running the rebooted system, everything seemed fine and the “CPUID” tool did indeed report that it was running at 2.7 Ghz. After a couple hours of running, using Sonar, Live and Reason I didn’t see any indication that the temperatures were getting out of hand. So that experiment worked OK.
The next step is to try 333 MHz which would give me an effective speed of about 3.0 GHz. Everything I’ve read indicates that that should be no problem for my system. We’ll see…
An interesting feature of this CPU is the “SpeedStep” option. Apparently, the system runs at a 6X FSB spped ratio most of the time and kicks itself up to 9X when additional power is required. This seems to work, as I can monitor the speed using the ASUS tool that comes with it.
ASUS also has a tool that supposedly lets you tweak BIOS parameters while running Windows (although the settings will clearly not take effect until the next reboot) but I have heard people have reservations about using that. It also makes me nervous that even the most recent version of AI Suite will CRASH if you set it to run in “Turbo mode.” So I don’t fiddle with those settings.
update feb 2011
Distilling many detailed articles about Q6600 CPU overclocking… The most recent BIOS installed on our ASUS P5E motherboard is 1201. It appears that the SpeedStep option has disappeared. That’s weird since I thought that was an important feature of the Q6600 CPU.
I’m currently just running the cpu with an FSB value of 325 MHz. At the 9x multiplier, that comes to an effective CPU speed of 2.925 GHz, about a 22% speed boost. I have been tinkering with the CPU voltage, since one article says the biggest contribution to CPU heat generation is that voltage. I’m going to try to run it at 1.25V and see how that goes. Everything I read does warn me that the only serious problem with the P5E mobo is a serious voltage droop under load. The BIOS “Loadline Calibration” feature is supposed to compensate for this.
update mar 2011
I have been running fairly well without crashes or hangs using 325 MHz FSB and 1.25V CPU as discussed about for about a month, but I have noticed odd little artifacts. When I exit Ableton Live (8.2) a process keeps hanging around as shown in the Task Manager and sometimes never ends.
Finally yesterday I downloaded a minor update (8.2.1) to Live and installed it. When launching it I suddenly started to see error messages about a VSTi plug in I use a lot (Zebra). This was odd and seemed mysterious. After some research I reduced the FSB but still saw occasional error messages. I increased the CPU voltage in the BIOS to 1.50VDC and returned the FSB to 325 MHz and now the system gives no errors, and I haven’t yet seen the Live hanging process. The temperatures as shown in Pure Temp and still always under 45C. I’m going to run it at this setting for a while and see if everything is stable.