HANDS ON GUIDE

Extreme Overclocking

Changing the FSB and vcore are only the first steps when it comes to overclocking. We spoke to two seasoned overclockers, both members of the Extreme Prometeia UK (EPUK) forums, to get some tips about tweaking a PC for maximum performance, as well as how to get started with sub-zero cooling.

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‘My main benchmarking system is cooled by a Mach II, and uses an Asus P5K3 motherboard and 2GB of CellShock DDR3 clocked at around 1,800 MHz. The other rig is a test bed with a water-chilled loop for the CPU,’ explains Peter. ‘The spec changes regularly though – I’ve just ordered a DFI LanParty UT P35-T2R. I’ll try it on the water-cooled rig, then the Mach II. Having good components is very important. There’s always a point at which the PC won’t reach [a certain overclock], no matter what you do.’ Kenny agrees that it’s important to know your hardware, but advises against chopping and changing too much. ‘My CPU is a fairly average overclocker. If I found a chip that would offer a significantly better MHz/voltage ratio then maybe I’d swap, but I try not to switch components for small gains – bangs per buck are important to me.’ That said, Kenny uses RAM that’s ‘a bit special’. ‘It’s 2GB of TeamXtreem RAM – a split Signature Edition between OnePageBook (a RAM guru) and myself. The SPD is one of a kind, and the sticks were chosen from ‘the top bin of the top bin’ when Team was building up stocks of their PC6400 3-3-3 sets.’

Number 5: Everything is connected

‘A great chip with poor cooling won’t shine,’ says Kenny. Try to keep everything balanced and bear in mind when the next bottleneck is likely to occur. Is the chip getting too hot? Will you run out of FSB? Can the PSU keep up? For a really high overclock, the bottleneck is usually cooling, although this doesn’t necessarily mean the temperature. After that, it’s usually the FSB. The board and CPU both have to be capable of running the desired FSB, and with a low multiplier on all but the top-end chips, it can be a problem. After that, I’d rank the PSU and the motherboard’s CPU voltage supply gear.’

‘When it comes to overclocking graphics cards, the bottlenecks are cooling, voltage and power – usually in that order. Most GPUs don’t offer real voltage options, so volt mods are almost essential for good clocking. My GeForce 7900GS can hit around 600MHz at stock voltages when water-cooled, and it will reach around 740MHz with a full volt mod.

Number 6: Ditch your case and buy a multimeter

‘I don’t use cases any more, as I’m lucky enough to have the space to leave it all set up on a table. That allows easy multimeter probing, as well as providing great airflow and easy access to all the components,’ says Kenny. ‘Don’t automatically believe what your BIOS tells you. With my DS4 board, some of my RAM timings don’t match what I set in BIOS, and the RAM voltage is 0.1V too low. Never trust a software reading – always use a multimeter. I realise that this method isn’t for everyone, but for trustworthy and accurate monitoring, it’s the only way.’

Number 7: Get into memory

Both Peter and Kenny think that people underuse memory timings. ‘You can obtain quite a boost from playing with the memory, even if you don’t overclock the CPU. It’s trial and error – most new boards have a host of memory controls, from voltage to changing timings,’ says Peter. Kenny concurs. ‘People are too concerned about their four primary RAM timings – the subtimings help as well,’ he explains. ‘Once Windows is [safely] installed, I return to the BIOS and set all the RAM timings manually. My primary RAM timings are 4-4-3-6 at 500MHz, and my subtimings are fairly tight. “Write to Precharge” and ‘”Write to Read” delays are fairly important timings for P35 and I have both set to 10. The Nvidia 650i and 680i chipsets really benefit from having tRC tightened up.’

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