Monday, 2 January 2012

The Importance of a Stable PC

I'll admit it, I overclock my PC. My CPU, an Intel i5 750, is running at 4013mhz while my GPUs are overclocked around 20%. I even have my PCIe speed overclocked a little - this is something I will touch on later as I did some benchmarks on that.

So, overclocking is a topic all unto itself, but once you've got your hardware at speeds you like it is extremely important to test it. When I first overclocked I ran 8+ hour Prime95 stress tests on the CPU and RAM. I recall one time it developed an error after 5 hours, so I bumped the voltage a single increment and then it passed the full overnight test.

However, lately I'm less interested is spending a weekend perfecting the overclock and leaving my PC running full tilt overnight. There is a type of stress test called LinX which is very sensitive to instability. It also causes more heat to develop than Prime95. I use the Intel Burn Test for this.

I find IBT will generally find an error in the CPU at low RAM usage settings after around 30 runs. However, it is a little harder to find a RAM issue (or something else). The generally accepted practice would be to max out the RAM usage with IBT. This, however, takes a long time. Roughly 5 minutes per pass for me with 8 gigs.

Another option for testing RAM is a test called Memtest86+. It also takes a while but it will fully work your RAM. I use it rarely, but it is good to have.

Anyway, what prompted this blog is Battlefield 3. I've put hundreds of hours into games at my current overclock settings with relatively no issues. For example, Skyrim, I've logged just over 100 hours and the only crashes were the well known "Crash To Desktop" which I was able to fix with some user created mods. BF3, on the other hand, either CTDs or else it Blue Screens altogether. It usually doesn't happen until after a few hours of gaming, either.

I know my temps are fine, so the culprit is either software or hardware. It's easy enough to blame the software, but especially when overclocking, it is very important to be absolutely sure you can rule out hardware. So, I ran 5 passes of IBT at max RAM usage and, lo and behold, I got an error on the 3rd pass. I then ran 20 passes at low RAM usage and it passed fine. My fix, then, was to go into my BIOS in increase my RAM voltage a tick. My RAM is rated for 1600mhz CL8 at 1.65V, but the thing is when you load up 4 sticks of RAM it takes more juice overall. Possibly increasing the IMC voltage would help, but instead I set DRAM to 1.67V. So far so good, but if I get any more issues and am able to fix it, I'll write an update.

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