Overclocking

The information in this section has been graciously provided by my very knowledgeable friend jkesa.  A few things you should be aware of before entering any overclocking adventure are to make sure you have adequate CPU cooling, good quality memory, and a very good power supply that is able to sustain stable voltages as you begin to overclock your system.  Generic power supplies and stock heat sinks along with many "value series" memory modules will not allow you to overclock very much, if at all.   We make no guarantee of success, and take no responsibility if you damage your system while attempting to overclock your system using the methods provided below.  Use this guide at your own risk!!

Overclocking Tutorial Provided by jkesa

The L12 Mod

The L12 mod changes the default Front Side Bus setting of the processor.  The NF7-S ver 2 boards seem to prefer 333fsb processors, while the earlier versions seem to prefer 266fsb processors.  Many users report FSB increases after this mod of 10-25 fsb extra, while a very few have reported no increases at all.

There are a few ways to perform this mod. One way, which does not leave marks on the cpu, is to insert very thin "u" shaped wires into the cpu socket at the appropriate places. Then inserting the cpu shorts the pins together at that location. Another way, which I prefer, involves using rear window defogger paint between the cpu pins on the underside of the cpu at the appropriate places. Rear window defogger repair kits containing the electrically conductive paint are available at Pep Boys or any similar auto parts store. I use a bent needle or sharp toothpick as a brush. You will also need a mounted magnifying glass to see what you are doing. I like this method because there
is no chance of thin wires falling out. Rear window defogger paint can also be cleaned off with acetone or nail polish remover. More information on this mod is available from the source at Xtremesystems.org.  Other cpu pin mods are available at ocinside.de.

Overclocking the Abit NF7 in General

One of the biggest selling points of the NF7 series is its overclocker friendly features. The NF7 has 5bit FID Override technology, which automatically unlocks the non Super Locked  (cpu's made before approximately week 39 of 2003 and mobile) AMD Tbred and Barton processors. The board provides a wide range of multiplier adjustments from 5X to 22x for AMD processors that are not super locked. Front side bus is adjustable from 100mhz to 300mhz in approximately 1mhz intervals. CPU voltage is adjustable from 1.1 to 2.3volts. DDR SDRAM voltages can range from 2.6 to 2.9 volts. There are voltage adjustments for agp and chipset to further tweak the system as well as a variety of CPU to FSB ratios. All these adjustments can be accessed from the Softmenu 3 in bios on one convenient page. The NF7 series also features the locked pci bus, so that overclocking the fsb will not affect or overclock any other pci devices. The board has enough features to keep an avid overclocker tweaking for days.

Cooling

As with overclocking any system, keeping components cool is of utmost importance.  The thing to keep in mind is that more voltage almost always results in more heat.  With more heat, a way must be found to get rid of it.  Whether using air cooling, water cooling or heat pump technology, effective quality components must be used.  And a quality thermal paste like artic silver or shin-etsu should also be kept in mind to reduce the temps a few C more in degrees.  Even though socket A processors in theory can handle 80-90C, strive to keep temps under 55C. Better yet, under 50C.

Air cooling is chosen by most NF7 overclockers not because of its efficiency but for its relative ease of installation and use.  I wont go into water cooling and heat pump cooling here.  When purchasing a heatsink for the NF7, spending a little more will generally save you money in the long run.  When most beginning overclockers see how far the NF7 will allow them to overclock, they want more, and discarding a weak sink for a better one results in no savings.  Some companies that make excellent heatsinks are Thermalright, Swiftech, Zalman, and Thermaltake, but just recently.

Chipset cooling is also very important on these boards.  Upon first receiving the board, it is highly recommended that the northbridge heatsink be taken off carefully and the thermal paste underneath it be spread out properly.  Even better would be to clean it off and reapply with some quality paste like artic silver.  Higher quality northbridge heatsinks are also available for the NF7.  Performance increases by doing this are hard to quantify, but it certainly does not hurt.  Installing a heatsink on the southbridge is also highly recommended.  It gets finger burning hot. The southbridge is where the IDE UDMA133, USB, Lan,  PCI controllers and on the NF7-S, where soundstorm are located.  Some problems associated with the sound can be cured by a sink.  Various methods of attachment are described in the Abit USA cooling and case modding, and Nvidia chipset based motherboards forums. Just search on southbridge heatsink.  Mosfet heatsinks, also hard to quantify the benefits of, do not hurt either.  Because of the way the mosfets are mounted to the board, a fan on the back of the motherboard in that area, will provide effective cooling also.

Power Supply

The importance of a high quality power supply with plenty of wattage for all devices cannot be overstated.  Low voltages on any rail, with the exception of the negative voltages, can lead to problems.  A low voltage on the 3.3v rail, below 3.25 for example, can lead to not achieving a stable 200+ fsb.  Unusual negative voltages are no need for alarm. The NF7 itself does not use any negative voltage, and modern pci cards do not either. The exception being custom made pci cards.

Overclocking Tips for the NF7

Almost all settings needed for overclocking the NF7 series are available on two convenient pages in bios. The Softmenu 3 page and the Advanced Chipset Features page.

Testing for stability

Various programs are available for stability testing from this website. Prime95 is a good one.  Running a 3D video looping program like 3dmark01 while running Prime95 is an even better test of total system stability.  Running even more programs in the mix is even better.  Memtest86+ is a good program for testing memory. One thing to note is that a fail on test #5 of memtest does not necessarily mean a bad memory dimm. It could also mean a poor power supply.  SiSoft Sandra also includes a burn-in module that can be used as a quick and dirty stability and load temperature tester.

External clock

If you have a super locked AMD processor, this is the main way to overclock your cpu. Super locked AMD cpus are those cpus manufactured after week 39 of 03.  Starting at stock settings for your processor, start raising the fsb in small increments and test for stability at each setting.  If its stable, check your temps and repeat. You may have to increase your vcore or vdimm  voltages to get stability. If you are lucky enough to have an unlocked processor, set it to a low multiplier like 7 or 7.5 and start upping the fsb until you find the limit. Then you will know how far your ram and NF7 will go uninfluenced by the processor.

Multiplier Factor

If you are fortunate enough to have an unlocked AMD processor, after finding out what the maximum fsb your ram and motherboard can handle, start increasing the multiplier. For optimal performance, a compromise will have to be made between high total overclock and a high fsb. A high fsb with a fairly high total overclock will give you the best performance for gaming and other applications. As above, you may have to raise your vcore or vdimm voltages while keeping an eye on temperatures.

Agp frequency

Adjusting the agp frequency above 66mhz will give only a small performance improvement at the risk of video card instability and or damage.  Radeon cards will generally go unstable at a lower frequency than GeForce cards. Adjusting the agp frequency to anything but 66mhz is not recommended. A much larger video card performance improvement can be had by overclocking the video cards gpu core and memory.

CPU/FSB Ratio

The CPU/FSB ratio should be kept in a 1/1 ratio for max system performance.  Most users use 6/6 and some others use 3/3 and 5/5.  Even though there are only relatively tiny differences between these ratios, experiment using SiSoft Sandra memory benchmark and stability testing to find the best setting for your system.  Only if you have a poor cpu or poor ram should you ever consider using a non 1/1 ratio.

CPU Interface

CPU Interface should be set to enabled as noted in the bios section. CPU Interface disabled will generally give you a higher front side bus overclock at the expense of performance. An estimate of 15 to 20 more fsb is needed to compensate for memory performance with CPU Interface disabled.

Voltages

Vcore -  Vcore is the voltage required for the processor. AMD socket A processors presently have default vcores ranging from 1.35volts on mobile processors to 1.75volts. Generally the NF7 under volts the vcore by a small amount. Generally accepted by the O/C community, relatively risk free, maximum vcore on present socket A processors is 1.85 volts with proper cooling.  Any use of other than stock voltages for your cpu is done at your own risk and we take no responsibility for any damage to your cpu should you decide to raise the vcore voltages.  Some have run processors a long time with much more voltage, others will say 1.85volts is close to suicide. Range is 1.1volts to 2.3volts.

DDR SDRAM Voltage -  This is the voltage require for the memory, generally referred to as vdimm. Some dimm sticks, like Samsung are very voltage hungry. A few others wont boot if the voltage is too high. Checking the manufacturers max voltage rating is suggested before raising the DDR SDRAM voltage.  Range is 2.6volts to 2.9volts.

Chipset Voltage - This is the voltage supplied to the northbridge. Some users need a higher chipset voltage for high fsb overclocks. Others do fine leaving it at the default 1.6 volts. Range is 1.4volts to 1.7volts.

AGP Voltage -  This supplies the voltage to the agp video card. Most video cards do fine at the default 1.5volts. A few stubborn Gforce cards need 1.6volts to work. Range is 1.5volts to 1.8volts.
 

Tweaking and Overclocking Memory

Dual Channel

Dual channel is enabled in the NF7 by using 2 or more dimms and placing one in dimm slot3 and the other in any other dimm slot. Single Channel is active when dimms are in dimm slot1 and dimm slot2. To recap, slot1 and slot2 are one channel and slot3 is the other channel. Although not officially supported, many users successfully run dual channel with 3 dimms. A correct example on how to do this is to have two 256mb dimms in slot1 and slot2 and a 512mb dimm in slot3. Having the dimms closely matched as to manufacturer, speed and batch will increase your chances of running dual channel successfully.
Benchmark memory performance increases with dual channel versus single channel will be small, approximately 5%. This is because the AMD processor cannot utilize all of the memory bandwidth dual channel provides. However, because of the way the NF7 nforce2 northbridge and southbridge operate, not all of the excess memory bandwidth goes to waste. Some of it is used for the NF7-S soundstorm for example, making the NF7-S onboard sound less cpu usage intensive than it might otherwise be.

Memory in General

The NF7 series requires good memory and not all memory is compatible. Check the Abit and memory manufacturers website for compatibility. Memory manufactures generally list the default memory timings in a) ascending order of importance. For example : 8-4-4-3. Or b) in descending order of importance. For example : 3-4-4-8. T-ras being the last number in this case, and is the setting that will affect memory speed the least.

BIOS Advanced Chipset Features

Memory Timings

Set to Expert to enable custom settings. Abit lists the memory timings in ascending order of importance from top to bottom.

Row active delay

The delay that results when two different rows in a memory chip are addressed sequentially. Also known as T-ras. Values range from 1 to 15. Most NF7 users report better memory performance with a value of 11 or 10. Setting this value too low can result in data corruption. A good way to think of this setting is the time a page in a book is available to be read, before the book is closed and opened to a new page. If the book is closed before the page is fully read, you have to reopen the book to the same page to read it again, which means you wasted time progressing to the next page. However if you are done reading the page, leaving the book open too long also slows your progress to the next page.

RAS-to-CAS delay

The number of clock cycles that elapse between the row address being determined and the column address being sent out.
Also known as T-rcd. Values range from 1 to 7. In most cases its best to leave this setting to the factory spec of your ram. Decreasing this value to 2 will improve performance at the risk of instability.

Row-Precharge delay

The number of clock cycles needed to precharge the circuits in order that the row address can be determined. Also known as T-rp. Values range from 1 to 7. In most cases, like for T-rcd, it is best to leave this setting at your factory ram specs. Decreasing it to 2 will also improve your performance at the risk of instability.

Cas Latency Time

The number of clock cycles that elapse from the column being addressed to the data arriving in the output register. Also known as T-cl. Values are 2.0, 2.5, 3.0. Setting this value lower will give the greatest memory improvement tweak. If the system becomes unstable, youll have to increase the value.

System BIOS Cacheable & Video Ram Cacheable

These two settings are throw-backs to the days of slower computing and the DOS operating system. Disabled is the preferred setting for overclocking. However, it makes little difference either way. Values are Enabled/Disabled.

AGP Aperture Size

This is typically set to one-half of system memory. However, no performance increase has been noted setting it above 256mb. The Windows operating system has the control over the AGP allocated memory size. Values are 32M, 64M, 128M, 256M, 512M.

FSB Spread Spectrum & AGP Spectrum

For overclocking, these two settings are normally set to disabled. If you experience radio or tv interference, you may want to experiment with these. Values are Disabled, .50% AGP and FSB, 1.00% FSB.

CPU Thermal Throttling

Normally set to disabled for overclocking. This setting does not work they way it does on Intel systems. For those interested, a complete discussion of nforce2 CPU Thermal Throttling can be found at rojakpot.com. Values are 12.5% to 87.5% in 12.5% increments and Disabled.

Enhance PCI performance

Normally set to Disabled for overclocking. If Enabled, this setting can help increase the performance of some quality pci cards. Values are Enabled/Disabled.

CPU Disconnect Function

Also normally set to Disabled for overclocking. Enabling this setting will enable the winnt kernel cooling function, resulting in lower idle temps. Load temps will remain the same. It also decreases Hard Drive performance, but not nearly as much as on the VIA chipsets. Values are Enabled/Disabled.

AGP Data Transfer Rate

Normally set to Auto for overclocking. It can be used to force a lower AGP transfer rate. The Windows operating system controls the top AGP speed. Values are 2X, 4X, 8X and Auto depending on video card.

AGP Fast Write Capability

Normally left at the default of Enabled for overclocking. If you are experiencing instabilities with your video card, you may want to try Disabled. Values are Enabled/Disabled.