- Stress Testing
There's a point at which your system is "over"-overclocked for the combination of components and cooling you've got. The trick is determining exactly when is "too far", especially with the somewhat misleading guidance from some overclockers along the lines of "If it's not on fire, it can go higher". Here are some helpful free tools which should help you determine whether your system is acceptably stable at your current level of overclock:
- 3DMark2003 - A graphical benchmarking tool, can also be used to determine whether your system will be stable for gaming. Leave it on default settings and run it several times in a row. If your PC has frozen or rebooted, crashed back to the desktop, or you can clearly see texture flickering or small glitches ("artifacts") or dots appearing randomly ("sparkles") then your system is overclocked too far. Try additional cooling, and failing that simply scale back the overclock on either your video card and/or your CPU.
Note that you need DirectX9.0 (see Device Drivers section) to run 3DMark2003. If you don't want to install DirectX9.0 and you have DirectX8.1, you can download and run 3DMark2001SE from the link above, although it is much less indicative of current and upcoming games and hence won't be as good a test of your system. Also note that you must have 3DMark2001SE version 330 to allow it to run under DirectX9.0. There is also a patch to bring 3DMark2003 up to the latest version. Patches for both these products are available from the Futuremark site.
- RthDribl - that stands for Real-Time High Dynamic Range Image-Based Lighting. If you have a recent graphics card with full support for DirectX9.0, specifically Pixel Shader version 2.0 then this demo will use those features to render truly amazing lighting and details on a range of models, with a range of backgrounds. Running this demo in fullscreen mode at high resolution will stress your graphics card and if left to run for a while will show up instabilities in the form of lockups, crashes, or artifacts. Definitely worth a spin if your system is up to it.
- Codecreatures - Another good graphical benchmarking similar to 3DMark, which also doubles as a stress test for your system. Run the benchmark several times and again if your system crashes or displays anomalies then you've overclocked too far.
- Prime95 - A program which will effectively stress test your CPU and memory subset. Once you've installed the application, to run the actual stress test run Prime95.exe and choose the Just Stress Testing button. Next, under the Options menu select Torture Test to start testing. Also read the document Stress.txt that comes with the program when you get the chance. It will explain more about CPU stress testing and how Prime95 helps uncover instability. The program recommends running the torture test for between 6 - 24 hours. A heavily overclocked PC may crash within a few minutes of running the test, however if your PC lasts over 2 hours it should be stable enough for gaming.
- SiSoft Sandra - Sandra is a benchmarking and system information utility which is quite handy. Once you've installed Sandra, it has a range of modules for providing system information, but some are primarily for benchmarking and stress testing. Run the Burn-In Wizard module and you'll see that it allows you to select any or all of the 6 major benchmarking modules in Sandra. If you then continue, it will allow you to choose the number of times you wish to run these tests, or to simply run them continuously until stopped. I recommend running all but the File System and CD-ROM/DVD benchmarks in a continuous loop for at least 2 hours to test for stability. As always, if your system crashes or freezes at any point you know something's not right with your overclock. If you want to pinpoint the problem, try running individual modules on a loop (such as the CPU Arithmetic Benchmark by itself) and if there's a failure you'll have a better idea of which component is to blame.
- Memtest86 - Memtest86 is a memory test for x86 architecture systems (Intel). It tests your memory before anything else loads up, so it really is a good stress test/check of your actual RAM and memory subset. To use Memtest download the latest zip file and extract the contents. Run the Install.bat file from the archive and enter a blank 1.44MB floppy as prompted. To run Memtest, leave the floppy in the drive and reboot your system - it will run from the floppy.
- DocMemory - A memory testing utility which can identify RAM-specific problems by stress testing your memory. You will have to install the program on a floppy disk, then reboot your system booting from this floppy. Upon reboot it will start DocMem and default to the Stress Test mode. Simply choose the Test button to start the testing. If you have any crashes or errors then it's quite clear the problem is with your RAM.
Of course, if you have any current games with a demo mode or a benchmarking utility (such as Benchmark.exe in Unreal Tournament 2003) then I suggest running those for a lengthy period of time as well to see how stable your system is in a 'real world' gaming environment.
The aim of any system, overclocked or not, should be a combination of stability and performance, not one or the other. There's no point having a blindingly fast system if it crashes most of the time. Forget PC benchmarking "drag races" or bragging rights, the ultimate aim of a computer for every day use is to run your programs quickly and dependably. By the same token - and the reason why this guide was written - there's no point having great hardware if you're not going to work it to its full potential, so I am by no means saying that you shouldn't overclock - just that you should do it correctly.