[graysky]

CPU TM function – enable. Option affects CPU protection/throttle management to help you when you don’t realize you’re pushing your chip too hard.

Execute Disable Bit - enable. XP has a setting to help with virus protection and requires this set to enable.

PECI – This stands for Platform Environment Control Interface - disable or enable. This affects how your DTS (Digital Thermal Sensors) report the core temps of your CPU. I have mine enabled and have read several posts now that suggest having it enabled does indeed give more accurate core temps. I can’t say if you want it on or off in your system.

According the Asus P5B-Deluxe FAQ, this setting toggles between two temp modes.

Note: if you’re using a real core temperature monitoring application such as coretemp (mentioned and linked above), this setting has no effect that I can see.

SpeedStep - Automatically lowers the multiplier from its max. (9x for the Q6600) to 6x when the machine is idle. The result is less power consumption and heat production. It goes back up to 9x when you start to get a CPU load. Disable initially, enable later on and see if the system remains stable. This is a power savings option.

Why do you care about power savings? Increased power consumption translates into increased heat production. As well, power costs money and unless generated from a nuclear power plant, creates carbon dioxide gas. It’s true that energy savings will only matter when the machine is idle, but odds are your machine will spend most of its time at idle unless your run an app like fold@home or seti@home etc. Let’s assume for the sake of discussion that enabling these saves you 10 cents / day. A few pennies per day will add up over time. Using the dime-per-day as an example for a machine running every day is roughly a savings of $35 per year – not too shabby.

Tomshardware.com's power savings article reported a savings of 12 full watts by enabling speedstep on their test system.

Second thing you'll want to do is dial in the manufacture’s specs for your specific memory. Also take care not to exceed the design specs for your memory initially. We want to minimize the number of variables to deal with on a first time overclocking. In other words, if your machine isn't stable, you want to be sure it's due to the CPU settings, NOT the memory timings.

Where can you get the manufacture’s specs? Try their website or the product packaging.



Enter in the first four timings (4-4-4-12 in my case) and don’t mess with the default or auto values for the “sub timings” at this time. You can do that after you get a stable overclock.

The only other setting worth mentioning here is the so-called “memory remap feature.” If you are running with more then 3 gigs of memory, and you want to actually have the BIOS/OS see it, you’ll need to enable this. Also enable this if you’re running a 64-bit operating system.

Next, find the section where you can control the nuts and bolts of your system. On my P5B-Del I had to switch the AI tuning to "manual" mode to see these options:



CPU Frequency - This is the FSB in MHz. Set it to whatever you’re planning to multiply by 9x (333 in my case).

DRAM Frequency - This the speed your RAM will run. Make sure you don’t exceed the amount for which your specific RAM is rated.

Most good boards will offer several fsb:dram dividers. Some common ones are listed below. Assuming that you’re using a 333 MHz FSB the ratios are:

FSB : DRAM
1:1 = 333 MHz : 667 MHz
4:5 = 333 MHz : 833 MHz 
2:3 = 333 MHz : 1,000 MHz
5:8 = 333 MHz : 1,066 MHz
3:5 = 333 MHz : 1,111 MHz
1:2 = 333 MHz : 1,333 MHz

Now, if you’re running @ a 400 MHz FSB, the ratios become:

 FSB : DRAM
1:1 = 400 MHz : 800 MHz
4:5 = 400 MHz : 1,000 MHz 
2:3 = 400 MHz : 1,200 MHz
5:8 = 400 MHz : 1,280 MHz
3:5 = 400 MHz : 1,333 MHz
1:2 = 400 MHz : 1,600 MHz

You can calculate these yourself with this formula:

DRAM Final Clockrate = (2 x FSB)/Divider

Example, 2/3 divider @ 400 MHz FSB: (2 x 400 MHz)/(2/3) = 1,200 MHz

Running in 1:1 mode is termed, “synchronous mode.” If you use a higher frequency, you’re running is so-called “asynchronous mode” which offers marginal speed advantages at the price of more heat and power consumption on a C2D/C2D Quad-based system for most users. Depending on your chipset, running in an asynchronous mode may require more vcores to some of your motherboard components such as the NB, IHC, and/or FSB Termination (more on these later).

PCI Express Frequency – Set this to 100 MHz. If you don’t, I believe the PCIe bus speed will increase proportionally with your FSB which is something you DON’T want to do to your expensive video board.

PCI Clock Synchronization - Use 33.33 MHz here. Again, if you leave the setting on auto, the PCI clock will creep up proportionally with your FSB which can damage cards you may have there aren't designed to run at higher frequencies.

Spread Spectrum - disable.

Memory Voltage - Read the specs for your memory. My DIMMS can use up to 2.2v. You can damage your memory if you overvolt it.

CPU VCore – THIS IS KEY! This single BIOS setting will have the largest effect on your processor’s operating temperatures! Again, read on to the section entitled, “Stress Testing and Minimizing Your Vcores.”

It needs to be enough to run stable, but not too much or else you’re just wasting power and creating a ton of heat. This is particularly true with multicore processors!

In case you’re wondering what Intel recommends for your processor, find your chip on Intel's Processor Finder. The Q6600 is between 0.85 – 1.5V.

In my experience, a setting of “auto” ALWAYS over-estimates, but for your first boot, just leave it on auto. The next section of this guide covers stress testing whose goal is to verify stability and to minimize your vcore. For example, once you verify that you can run stable for several hours of stress testing, you'll want to come back and minimize this voltage until you become unstable again. Then simply add a little back. As you can see, my system runs stable @ 9x333 using 1.2625v.

Originally Posted by ”Related topic”

Why do you care? Heat (power) increases with the square of voltage. It increases in a linear fashion with frequency. What does that mean? It means that as your FSB goes up, so does your heat, but as your vcore goes up, your heat goes up exponentially.

An increase in processor operating frequency not only increases system performance, but also increases the processor power dissipation. The relationship between frequency and power is generalized in the following equation: P = CFV^2 (where P = power, C = capacitance, V = voltage, F = frequency). From this equation, it is evident that power increases linearly with frequency and with the square of voltage.

I quoted the above statement from an Intel document. It has been removed from intel.com and used to reside at the following link: Missing Intel Document. I managed to find a copy of the pdf file in one of my backup sets. Knuspar from guru3d kindly agreed to host it here.

The title of the document is, "Intel® Core™2 Extreme Quad-Core Processor QX6700Δ and Intel® Core™2 Quad Processor Q6000 Δ Sequence Thermal and Mechanical Design Guidelines." It’s dated Jan 2007 and has an official Intel Document Number of 315594-002. I took a screenshot of section 4.1 on page 31 (where the above quote came from):



To illustrate, consider this analysis of two difference vcore settings and the temps they produce on my Q6600 @ stock settings (9x266=2.40 GHz) as well as running overclocked (9x333=3.00 GHz). The two voltages I used were 1.1375V and 1.2625V set in the BIOS that correspond to the two clock levels of 2.40 GHz and 3.00 GHz respectively. In case you’re wondering, these translated into 1.112V and 1.232V in Windows as read by CPUZ.

Prime95 ran for 30 minutes and the temperatures were averaged over the last 10 minutes of those runs (well after they stabilized). Room temp was 75-76 °F. Notice that the difference in voltage is ONLY 0.120 V or 120 mV, but this seemingly small difference brought the load temps up by an average of 6-7 °C per core!

Run1 (9x266 @ 1.112 V), Average temps (°C): 51,52,50,50
Run2 (9x266 @ 1.232 V), Average temps (°C): 57,58,57,57
Differences (°C): +6, +6, +7, +7

Now if I add a faster FSB, they increased further:

Run3 (9x333 @ 1.232 V), Average temps (°C): 61,61,60,60
Differences from lowest voltage (°C): +10, +9, +10, +10
Differences from same voltage (°C): +4, +3, +3, +3

The same thing holds true for speed in a car: energy = 0.5mv^2 where m is mass and v is velocity. This is the basis of the old expression, "speed kills." You generate way more energy driving 75 MPH than you do driving 55 MPH since energy and velocity have an exponential relationship. Take a 5,500 lb SUV as an example; its energy nearly doubles as a result of that mere 20 MPH increase.

Energy @ 55 MPH = 754 kJ
Energy @ 75 MPH = 1,402 kJ

The last four voltages are also required to make a stable system. Leave them on auto for now. On my system, I lowered my chipset temps by about 4 °C by lowering them to the values you see in the pic.

As I mentioned earlier, if you’re using high memory dividers (a.k.a. running your memory in asynchronous mode), you might have to manually tweak your NBvore and your ICH vcore to get the memory to run stable. For example, my Q6600/P5B-Deluxe system required me to up the NB vcore by +2 steps and the ICH vcore had to be set to the maximum value or else I couldn’t run my PC1066 memory at the higher dividers.

My X3360/LT P35-T2R system on the other hand, didn’t require nearly that much extra to run in the 5:6 divider.

In general, the P35 chipset is better than the P965 in this regard. I have read that the X38/X48 are on par or slightly superior to the P35.

Okay, save your settings and hopefully your machine will complete the POST.



If it doesn’t, and assuming you set your voltages to Auto, some common reasons are:

• Memory voltage too low
• Memory timings too aggressive
• FSB too aggressive

If you complete the POST, and make it into windows without a blue screen or reboot that's a good sign. Now on to the testing. Now that you're in Windows, load up CoreTemp or HWMonitor and have a look at your core temps when idle.



They should be well under 50 °C unless it's REALLY hot in your room, see the end of this document for more on how ambient temps affect your CPU load temps. There are a number of things you can do to bring down your idle and load temps. Again, see the end of this guide for some suggestions.

Let's stop here and figure out what the red-line for temps should be... for my B3 stepping of the Q6600, I don’t want to exceed a few degrees over Intel's 62 °C limit for any sustained period of time. The G0 stepping chip tolerates 71 °C, so you're probably safe a few degrees above that. You can decide on your own "red line" if you disagree with my admittedly conservative numbers. Here is some information you can use to help: Intel's Processor Finder. Read the Thermal Specification section. Wondering what the deal with the stepping of the chip is? Have a look at this article that will explain it as well as show you some differences between the new G0 stepping quads.

I may be misunderstanding it, but as I read it, the thermal specs are the upper limit for the "case temp." No C2D or C2D quad processor actually has a sensor for "case temp" as defined by Intel. To measure this, you would need to place a sensor on the top of your IHS right in the center. C2D/quads have INTERNAL sensors (called DTS or Digital Thermal Sensors) but not external sensors. Some software and BIOS's can approximate this "case temp," but without a physical sensor there, you're just guessing.

The formula for reading core temp from the DTS is:

 Core Temp = tjmax – DTS
Where DTS is the number the DTS is reporting, and tjmax is a constant (which differs with processor model and sometimes within a processor model based on its stepping)

Note: There is no official communication from Intel as to the magnitude of tjmax for desktop/server C2D/C2Q chips! This makes calculating the “real” core temp tough since people are just guessing.

For example, a Q6600 (G0) stepping may have a tjmax of either 95 or 105 (again, these are people’s best guesses). If tjmax is 105, then Core Temp = 105 - DTS. THIS DOESN'T MEAN THAT THE LIMIT FOR THE CHIP IS 105 °C! In this example, let’s say the DTS value is 50. Therefore, Coretemp = 105-50 = 55 °C. If tjmax is 95, the math becomes 95-50 = 45 °C. Don’t worry about doing this calculation; all the temp monitoring software will do it for you. I only mention it so you can understand what’s going on.

I like to keep my core temps under 65 °C. I may be using a conservative number here, but I don't want to replace my chip anytime soon. If you don’t care about the longevity of your chip, you can likely use higher numbers. I have read about people running their chips right up to the factory shutdown/auto throttle down temp. It’s your chip, do what you want.

Load up CPU-Z to see what your vcore is at idle.



You’ll notice that the vcore in CPU-Z is different from the value you selected in your BIOS. This is normal and true for all boards. You’ll also notice it drops again when your machine enters a load state: again, this is normal and known as vdroop; some boards/chipsets do it worse than others. If you read at the end of the guide, some boards can be modified to eliminate or greatly reduce vdroop.