If the Prime95 test fails on any of the cores, you know your CPU either requires a little more voltage, or has reached its speed limit. I also monitor my CPU temperature with a program called HW Monitor to make sure it is not getting too hot. You can download the latest version of HW Monitor from our website here: HW Monitor download.
Overheating CPUs will eventually fail. In this way you can incrementally keep pushing your CPU a little higher each time until you approach the point where it can no longer pass stress testing. You then back it off to a speed you feel happy with based on your testing results for voltage and temperature. I like to run Prime95 for a full 24hr test just to guarantee that the CPU is stable at this final speed. On occasion I have seen CPUs fail Prime95 after an hour or two of testing. This is not stable enough for my liking. Some overclockers would argue that Prime95 is no longer the stress test of choice for CPU stability, and are using a program called LinX. LinX is based on the Linpack CPU performance benchtest, but I must admit I have seen quite a lot of anomalous results from the use of this program, including brand new CPUs failing at default clock speeds and voltages. Some would argue that this indicated that the CPU is faulty straight out of the box, however, I am not convinced, and can say with assurance that any overclocked CPU I have stress tested for 24hrs with Prime95 has always performed faultlessly in any normal usage scenario including high end 3D gaming, decompressing of large files and video editing.
Before I conclude this post there are a couple of points I want to raise which should be of interest to any potential new overclockers. I stated earlier that the major CPU manufacturers have been multiplier locking their CPUs for many years now and generally speaking this is true, however there are some exceptions. AMD has been regarded highly by the overclocking community for their “Black Edition” product range.
Selected models of CPU have been released with unlocked multipliers and given the Black Edition moniker. These unlocked CPUs make overclocking a lot simpler for the novice in that you do not have to run your system bus or memory frequencies outside default specifications, and can ramp up the speed of the CPU by simply increasing the clock multiplier. Intel also started to ship unlocked CPU models. Originally restricted to their “Extreme Edition” flagship models, which were also very expensive, Intel recently introduced a “K” series, with just a few selected models having unlocked multipliers.
These models usually attract a price premium of $30-$50 compared to the locked versions. Intel on the other hand has also attracted the wrath of overclockers with their latest “Sandy Bridge” Core i7 CPUs. The motherboard chipset architecture which applies to these new CPUs has been changed. The system bus has been linked to other buses on the motherboard such as USB and SATA, all using a single clock generator. These other buses do not like being run out of specification at all. The end result? You pretty much can't overclock any of the new “Sandy Bridge” based CPUs, unless you pay the price premium and purchase an unlocked “K” series model.
The community will be watching with interest later in the year when AMD are set to launch their new CPU range based on the “Bulldozer” architecture, and no doubt hoping for unlocked multipliers and great overclockability.
Here at DCA Computers our experienced technicians can configure and build any type of overclocked system you can imagine, ranging from mildly overclocked air cooled systems, right up to high end water cooling or even phase change based systems. You can call us any time on (02) 9634 2555 to discuss your requirements.
Glenn Howlett is the general manager of DCA Computer Technologies a computer retailer and support provider. Read more articles at the DCA Computers blog, follow DCA Computers on Twitter and become a fan on Facebook.