Overclocking Tips
Disable Features: As always, be sure to disable OC-hindering features before overclocking. In the CPU Feature menu (accessible from Advanced BIOS Features,) disable Execute Bit Support, C1E Support, Set Limit CPUID MaxVal to 3, and CPU TM function. If you do not see all of these options in the menu, press F4. In the Cell Menu, disable D.O.T. Control, Intel EIST Speed Spectrums, and Auto Disable DRAM/PCI Frequency. Lastly, for best results, set SLI-Ready Memory to EXPERT if available, and System Clock Mode to MANUAL.
Keep a 1:1 Divider between RAM and FSB: When overclocking, it is best to keep a 1:1 ratio between RAM and FSB, such that the base FSB speed = the base RAM speed. On reference nForce boards, a 1:1 ratio can automatically be obtained by setting RAM to "linked and synced." However, setting your System Clock Mode to LINKED on the P7N diamond does not result in a 1:1 ratio. To keep a 1:1 ratio when overclocking, you must set System Clock Mode to manual and do some math.
The math, fortunately, is rather simple. The important thing to remember is that the numbers set in the BIOS for FSB and RAM are rated, or multiplied speeds. The rated FSB speed set in the BIOS is the quad-pumped speed, so it is 4x the base FSB speed you want to match. The RAM speed is the double-data-rate speed, so it is 2x the base RAM speed you want to match. To keep a 1:1 ratio, simply set RAM to 1/2 your set FSB speed.
Below are some examples of popular 1:1 ratios, as set in the P7N BIOS.
* FSB = 1066, RAM = 533 (base speeds: 266mhz)
* FSB = 1333, RAM = 667 (base speeds: 333mhz)
* FSB = 1600, RAM = 800 (base speeds: 400mhz)
* FSB = 1800, RAM = 900 (base speeds: 450mhz)
Know your CPU's VID: The P7N has an odd way of setting vCore (your processor's voltage.) Unlike other boards where you simply set the voltage you wish to pump to your CPU (i.e. 1.3v, 1.45v, etc,) the P7N has you set the amount of voltage increase (i.e +0.0500 to stock, +0.1000 to stock, etc.) In order to know how much voltage you've set in the BIOS, you must know your CPU's default voltage. This is called VID, and is unique to each and every Core 2 CPU.
To find your processor's VID, you must use either Core Temp, Everette Ultimate Edition, or (I believe) CPUID Hardware Monitor. Each of these programs can be downloaded from the Internet, but note that Everette is trial-ware and may not display VID w/o paying for the full version. On a Conroe or Kentsfield processor, your VID will most likely be within the range of 1.2000v to 1.3500v. On the popular Q6600 G0, VID will likely not exceed 1.3250v, with most coming in around the 1.2500-1.2750 mark. On 45nm chips, VID will be lower, often below 1.2000v.
The amount of voltage sent to your CPU (according to the BIOS) is VID + the amount set in the BIOS. If you leave vCore on AUTO, then the VID amount is sent. Unlike the reference boards, the P7N will not guesstimate an increased voltage to match your overclock when vCore is left on AUTO. Note that this explanation does not account for vOffset or vDroop, which is explained below in its own section.
North Bridge Cooling: One of the more impressive aspects of the P7N Diamond is that the North Bridge seems to run genuinely cooler than on other 780i boards. While it won't run at breezy P35/X38 levels, NB heat shouldn't be as much of a concern on this board as on others.
Note that as of now, there is no easy way to accurately read the NB temp. The BIOS, the latest version of Everest, and HW Monitor report a MB temp, which according to MSI, is taken from near the center of the motherboard. You can feel for a hot NB (quite literally) by placing your hand on the NB heat pipe. If it feels too hot to touch for a short period of time, then your NB is running hotter than it should. (Note that this is not necessarily the case with other 780i boards, as they may naturally run too hot to touch w/o aftermarket cooling.) In this case, you may want to inspect the motherboard's heat pipe. Make sure that it's making proper contact with the board in all areas. Furthermore, you might want to remove the heat pipe all together and inspect the TIM. Often times, the TIM is applied poorly from the manufacturer, and replacing it can greatly reduce operating temps. If you do replace it, consider using an alternative to AS5, such as Arctic Silver Ceramique. AS5 is slightly conductive and can cause damage to your board if any of it gets where it shouldn't. If you use AS5, do not use it on the MOSFETS, as these are particularly sensitive components.
Lastly, if you plan for a high OC, you will likely have to raise NB voltage. Even though the NB runs cooler than on other nForce boards, you may still find it worthwhile to buy a small fan to blow air over the heat pipe. An Antec Spot Cool works wonderfully in this regard, as its easy to set up and does a good job. For example, at 1.425v, my NB heat pipe is never too hot to touch and the MB temp does not surpass 50c.
Suggested OC Software It's important to have the right software to monitor temps and stress test. Below is a list of recommended software.
Temp monitoring:
- Core Temp 0.97, Download from http://www.alcpu.com/CoreTemp/. This is perhaps the most popular temperature monitoring program available. Note that the latest version is natively compatible with Vista x64.
- Speed Fan, Download from http://www.almico.com/speedfan.php. This is a popular alternative to Core Temp, but many do believe Core Temp to be more accurate. Speed Fan, on the other hand, will read the board's other sensors and report processor load and voltage. Important: Note that Speed Fan will inaccurately measure G0 stepping temperatures by -15 degrees. If you use this program, you must compensate for this inaccuracy in the settings.
- Everest, Download trial from http://www.lavalys.com/. This is the grand buffet of monitoring and reporting programs, and will tell you everything you could ever want to know about your PC. For temp monitoring, it's on par with Core Temp, but it will also monitor much more. This is trialware however, and you will have to pay to access all features in the full version.
Stress Testing:
Prime 95 25.6, Download from http://www.mersenneforum.org/showthread.php?t=9779. This is the golden standard for stress testing. When you are honing in on your final OC, standard practice is to run the Prime95 Small FFT Torture Test on all of your cores from anywhere between 4 to 24 (or more) hours. (Although I find 8-12 hours to be reasonable unless number crunching is a primary function of your computer.) If running a Quad Core, be sure to run version 25.0 or higher as it will automatically run an instance on each core. Also, be sure to check "Round Off Error Checking" before starting the test. Otherwise many stability errors will go undetected.
OCCT 2.0.0a, Download from http://www.ocbase.com/perestroika_en/. An excellent companion to Prime, OCCT is best used to test NB and RAM stability and for running a quick processor stability test.
