This is the third article in a six-part guide book.

Overclocking would be a difficult task without the help of some specialized software tools. It is very beneficial to become familiar with stability/torture testing programs, as well as system information utilities. The following sections will outline some of the most popular overclocking tools and show you the basics.

Prime95

One of the best-known applications for CPU stability testing is Prime95. Prime95 was developed to search for very large prime numbers. The mathematical algorithms that Prime95 uses are also very effective when used for stress testing a CPU. The developers were thoughtful enough to add a 'Torture Test' option, which will report any inconsistencies and unexpected mathematical results.

Prime95 uses a simple GUI. The torture test can be found under the 'options' menu.

There are several options available for torture testing. Generally, I use the 'In-place large FFTs' setting , as it very heavily utilizes the CPU and tests a small chunk of RAM at the same time. If there is any instability in your system, it will become evident very quickly using this mode. Once you click 'OK' the torture test begins. Status messages will slowly pop up as tests are successfully run. You'll also notice that the Prime95 icon turns red while testing is in progress. You can continue to use your computer while the tests run.

To heavily test your RAM from within Windows, I recommend a custom test.

Setup your custom test like what is shown above, with the exception of the 'Memory to use (in MB)'. You want to set this value just slightly lower than your available physical memory. You can check how much physical memory you have left by going to your 'Task Manager' and clicking the 'Performance' tab. If you have 406MB remaining for example, you may want to specify 380MB. If you specify more than your available physical memory, Prime95 will not work terribly well, as it will spend a lot of time testing your 'virtual memory' (your hard disk) and will not stress your memory/CPU enough. This is precisely why I do not like using the 'Blend' test, as it tends to test your virtual memory, and as a result, is not intensive enough.

Just how long you should let the test run is up to you. Defining stability has always been a hot topic of debate. It is generally accepted that 24 hours of Prime95 testing is an excellent measure of CPU stability. True stability would mean that you could run a Prime95 'In-place' or any other Prime95 test for 24/7 without any errors whatsoever.

This screenshot was taken from a PC that appeared to be stable. Clearly after 11 minutes, Prime95 proved otherwise.

You can download Prime95 from the Short-Media 'OC Tools' download area here: http://www.short-media.com/download.php?dc=72

OCCT

OCCT is another CPU stability testing application. Some overclockers love OCCT and prefer it's much more modern look and feel to that of Prime95. Perhaps one of its most useful features is being able to interface with temperature/voltage monitoring software such as Asus' PC Probe and Motherboard Monitor 5. Another nifty feature is being able to halt the test if the CPU temperature reaches a certain value.

Clicking the 'Test' button will run a 30-minute stability test on your PC. I would not consider the OCCT 30-minute test to be a measure of 'true' stability. The 'Torture' option allows you to run a continuous stability testing run, which is better for long-term testing.

As an added bonus, OCCT will generate a whole slew of graphical plots based on your system temperatures and voltages throughout the course of the testing. This is really useful to see just how much of an impact heavy loads impose on your system voltages and temperatures.

You can download OCCT from the Short-Media 'OC Tools' download area here: http://www.short-media.com/download.php?dc=72

Memtest86+

Memtest86+ is one of the most widely used memory testing applications available. Short-Media's very own primesuspect has created a nifty guide that can take you through many of Memtest86+'s features, including how to burn a bootable Memtest86+ ISO image.

You can find that guide here:

http://www.short-media.com/review.php?r=276

If you are lucky enough to own a DFI NF4 or NF3 mainboard, Memtest86+ has been implemented right into the BIOS and you do not have to worry about bootable media.

When pushing your memory beyond its intended specifications, it is important to run numerous loops of memtest to ensure that your memory is stable. Memory may appear to be stable for the first few loops, but as the DIMMs begin to heat up, errors may begin to emerge.

By default, Memtest86+ will continually run nine consecutive tests. Using the 'configuration' option (press c), you have the ability to select any specific test to run. My personal favourite is test #5 (The 'Block Move' test). This test will just about always cause troubled RAM to fail. Test #8 is also very intensive and depending on your type of memory, it can be more effective than test #5.

As you can see above, 245MHz @ 2-2-2-6 timings appears to be stable after one loop of test 5. After a dozen or so loops, the memory will begin to heat up and errors may begin to appear. Terribly unstable memory will begin displaying errors after the first pass. In test 5, errors encountered will not be displayed on screen until each loop is completed.

Clearly, 257MHz was too much for this BH5 to handle. After the first pass, almost 4300 errors were detected. This memory overclock should be considered very unstable. If an operating system boot was attempted at this memory clock, a BSOD (blue screen of death) would most certainly appear before getting anywhere near the desktop.

So what if there were just a few errors you might ask? You may be able to use your system normally for a while but even one error occurring is one too many. Instability in your system will crop up sooner or later. You should be able to loop test number five/eight for hours, if not days without a single error. We'll get more into memory stability later, and explore the role the on-die memory controller plays as well.

CPU-Z

CPU-Z is a very handy tool for system tweakers and overclockers alike. CPU-Z is based on the Panopsys detection engine and can display all sorts of information about your system. It displays detailed information about your CPU, your clock speeds and even your basic memory timings. While browsing around online, you may have come across a 'CPU-Z' screen shot at one time or another. In terms of overclocking, CPU-Z is useful to ensure that the changes made in the BIOS are correctly reflected once you arrive in the operating system. When using memory dividers, CPU-Z can quickly reassure you of the 'true' memory frequency you have derived.

The SPD tab is also useful for displaying the memory OEM information, including model numbers and default timings at various rated speeds.

CPU-Z validation is another cool feature that has been released to keep liars at bay. Some people have doctored up CPU-Z screen shots using photoshop etc. CPU-Z validation produces a special 'cpu-z.cvf' file that you can upload to valid-x86-secret.com and have the information validated and posted online. Those wanting to show off their latest overclock can simply provide the x86-secret link to the published results.

http://valid.x86-secret.com/show_oc?id=33418

Here's one I did of my 3500+ at 2.6GHz. I actually find it just as quick as cutting and pasting a screen shot, and there is no question as to the validity of my CPU-Z information. Validation does not guarantee that an overclock is stable, but it's a step in the right direction.

You can find CPU-Z in the Short-Media 'OC Tools' download area here: http://www.short-media.com/download.php?dc=72

A64 MemFreq 1.1

A64 MemFreq 1.1 is a nifty tool that can do some of the overclocking mathematics for you. If you are mathematically challenged, this tool is for you. Simply enter your reference clock frequency, your CPU multiplier and a memory divider. It will calculate your DRAM frequency, and your CPU clock frequency for you.

A64 MemFreq does correctly calculate the DRAM frequency when using half multipliers as well. Be sure to read the 'Quick Note on Half Multipliers' for more information. It does not calculate your HTT clock frequency for you, so you'll still have to do that manually. This is a very simple tool that is handy to have in your overclocking toolbox.

You can download A64 MemFreq from the Short-Media 'OC Tools' download area here: http://www.short-media.com/download.php?dc=72

AMD64 MaxTCase

As mentioned in the 'Heat' section, all AMD processors have a maximum rated 'case' temperature. AMD provides a 'general' maximum temperature, however it is not unusual for 'E' revision processors to have slightly different maximum case temperature ratings from chip to chip. Some overclockers believe that the higher ratings from AMD relate to better quality silicon in the chip. My Winchester appears to be rated at 65 degrees, which is correct according to AMD's specifications. My Socket 939 Opteron listed a MaxTCase of 63 degrees, which is two degrees lower than AMD's official specifications. This is not an essential tool but is handy to determine just what AMD has rated your individual chip for.

Note: Mobile Athlon 64 processors usually have very high temperature ratings, and MaxTCase sometimes assumes that the tcase value is invalid. Perhaps this will be corrected in a future revision of the application.

You can download A64 MaxTCase from the Short-Media 'OC Tools' download area here: http://www.short-media.com/download.php?dc=72

Monitoring Tools

There are many applications available to monitor your system's cooling and electrical system. Variables such as CPU temperature, fan rotational speeds, and voltage readings are all essential to watch while overclocking. Many mainboard manufacturers have their own monitoring suites available. Asus uses something called the 'PC Probe' and DFI uses ITE's 'Smart Guardian'. These applications are platform-specific. For example, Smart Guardian can not be used to monitor an Asus system and vice-versa.

One of the most popular multi-platform monitoring applications is Motherboard Monitor 5 (as seen below). MBM5 has support for hundreds of different motherboards and is very customizable. MBM5 can even integrate into other applications such as OCCT and can import readings from other applications, such as ATITool.

On top of being able to monitor important system variables, it can even send e-mail notifications via SMTP if a reading exceeds a certain threshold. It can also take action and shut down your PC if it begins to overheat. Whether or not you decide to use MBM5, it is essential to have some type of monitoring application installed if you plan to overclock.

MBM5 can be downloaded from Short-Media's 'General Utility' download area here: http://www.short-media.com/download.php?dc=47

TIP: Official support for MBM5 has been discontinued, but you can still get your newer mainboard to work with a little bit of work. If you have one of the popular DFI NF3/NF4 mainboards, you can download pre-configured .INI files for MBM5.

There is a great thread at DFI-Street (DFI's support forum) that outlines how to configure MBM5 for the newest DFI boards.

Clockgen

Clockgen is a nifty application designed by the makers of CPU-Z. Clockgen allows some adjustments usually made in the BIOS, to be made from Windows. There are many different versions of Clockgen for popular mainboards and platforms. The popular nforce platforms have their own special versions of Clockgen.

Of highest interest is the ability to adjust your base HTT frequency (reference clock), and therefore your memory and CPU clock speeds. Being able to increase the reference clock from Windows can be convenient and especially useful if your mainboard lacks overclocking and tweaking options in the BIOS. You can also adjust your CPU multiplier and your vcore. Don't bother adjusting your PCI-E or AGP frequency from here as this will not improve your system's performance (See Bus Locking Section).

You can find Clockgen in the Short-Media 'OC Tools' download area here: http://www.short-media.com/download.php?dc=72

A64 Tweaker

A64 Tweaker is an application that allows the real-time adjustment of memory timings. It was designed by 'Code Red' of xtremesystems.org. If you are lucky enough to have a DFI NF3/NF4 mainboard, you'll recognize a lot of A64 Tweaker's timings from the BIOS. Many mainstream boards do not allow the adjustment of all memory timings and A64 Tweaker is the only way to fully take advantage of them.

A64 Tweaker is especially useful when testing the performance effect of minor timing changes. Having to reboot and adjust everything from the BIOS can be very time consuming. Once you've found the optimal timings in A64 Tweaker, you can simply revisit the BIOS and make the timings stick. A64 Tweaker also allows you to apply timing changes at bootup. You can save your settings to disk, and load up a specific collection of timings for benchmarking/everyday use.

You can download A64Tweaker from the Short-Media 'OC Tools' download area here: http://www.short-media.com/download.php?dc=72

Benchmarking

What may 'feel faster' is not always faster. Benchmarking helps to take the guesswork out of performance and gets some real-world data for comparison. There are many great benchmarking applications available today and we'll be using some of them throughout this guide.

Sisoft Sandra 2005

Sisoft Sandra provides a suite of benchmarks that are simple to use, and provides a comparison to a small database of results that others have obtained. There are some great CPU and Memory benchmarks that we'll be using in this guide including the 'CPU Arithmetic Benchmark', which focuses primarily on mathematical/float point calculations. There is also a CPU Multimedia benchmark that can take multimedia instructions into account as well (MMX etc).

There are also some other very popular memory benchmarks available. The Memory Bandwidth test is my favourite. It gives you a good indication of overall memory performance.

You can download Sandra 2005 from the Short-Media 'Diagnostic Tools' download area here: http://www.short-media.com/download.php?dc=58

SuperPI

SuperPI is a benchmarking application that calculates PI to millions of decimal places using the Gauss-Legendre algorithm. SuperPI is a fantastic stress-testing application and it also serves as a great CPU/Memory benchmarking application. Since SuperPI already knows the value of PI up to 32 million decimal places, it compares the calculated result to what is known. If there are any discrepancies, a hardware fault is likely the culprit. The 32M calculation usually takes around 25-30 minutes to complete, and is a great stability test. The 1M calculation is great for benchmarking. SuperPI heavily utilizes the CPU, L2 cache and system memory while testing.

You can download SuperPI from the Short-Media 'OC Tools' download area here: http://www.short-media.com/download.php?dc=72

3Dmark 2001SE. 2003, 2005

3Dmark 2001 SE was one of the original favourites for 3D Benchmarking. It is still heavily used today, but does not present much of a daunting task for modern graphics cards to handle. The system's CPU is usually the performance bottleneck in this benchmark, which also makes it a great CPU benchmarking application. Memory timings and memory frequency also play a large role in your 3Dmark 01' scores.

Unlike 3Dmark 2001, 3Dmark 03/05 are much more graphically demanding on your system and are much more GPU dependant for higher scores. Your CPU/Memory does still play a large role, but not nearly as much as in '01.

You can download 3DMark 2001/2003/2005 from Short-Media's 'Graphics Benchmarks' download area here: http://www.short-media.com/download.php?dc=20

Aquamark3

Aquamark3 is an older benchmark that is still used frequently. Aquamark calculates its total score based on a CPU score and a graphics score. Similar to the futuremark benchmarks, Aquamark scores will reflect everything from your graphics card overclock to your memory timings. This is certainly a classic that will likely be used for quite some time.

You can download Aquamark 3 from Short-Media's 'Graphics Benchmarks' download area here: http://www.short-media.com/download.php?dc=20

 

Next section: Testing and Finding Max CPU Clock

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