Make your PC go faster for free

Posted on 3 Jul 2009 at 12:03

• 
• 
• 

 1 of 3

Gallery

The two options to consider are the core frequency and memory frequency. Direct X 10-compatible graphics cards have a third option called shaders or stream processors, but as this speed is linked to the core speed, we'll ignore this option for simplicity's sake.

Graphics cards are normally more restricted than processors. As such, you may find the limit of your graphics card before you hit the 20 per cent level. To test for stability after each increase in clock speed, use the free 3DMark 06 graphics program.

Your graphics card's limit is characterised by 'artefacts', which appear on the screen. These are essentially graphical corruptions that might also be accompanied by your PC freezing. This is no cause for alarm, however, as you're not in danger of frying anything in your system. These glitches are simply your graphics card's way of saying you've pushed it too far. If this does happen, simply exit 3DMark 06 or reboot your PC and try lowering the clock speeds.

With RivaTuner installed, locate the small button below the drop-down menu in the graphics card/monitor information window. Clicking on this should bring up six or so coloured icons. Click on the one that looks like a graphics card and this should display the low-level system tweaks window. Tick the box labelled 'Enable low-level hardware overclocking'. You should now be able to move the slider bars. The changes won't be applied until you click Apply, so don't worry about accidentally moving the sliders.

Start by increasing the speed of the core in increments of 30MHz, then run 3DMark 06 once while watching for artefacts. Continue to do this until you see artefacts or the PC freezes. Go back to RivaTuner and reduce the clock speed by one notch, then overclock the memory, checking stability each time with 3DMark 06.

Unfortunately, we hit a wall with the memory frequency at just 25MHz above the default of 900MHz on our ATI HD 4830. Beyond this we experienced artefacts in our benchmarks. We were also unable to increase the core speed by more than 15 per cent, achieving just 650MHz. These figures are much lower, in terms of percentage, than most other graphics cards we've overclocked in the past, so the chances are you'll have more luck. We ran all overclocked tests with the memory set at 925MHz.

Before being overclocked, the ATI HD 4830 in our PC produced a frame rate of 46.9fps in Call of Duty 4 and 17.7fps in Crysis. With the core clocked at 650MHz, our PC managed a frame rate of 51.2fps in Call of Duty 4 and 19.5fps in Crysis. Overall this meant an increase of 8.4 per cent in Call of Duty 4 and 9.3 per cent in Crysis.

As we found that overclocking the processor also increased performance in games, we carried out a further run of the benchmarks with the processor overclocked at 3GHz combined with our maximum overclock on the graphics card. We saw a total performance increase of 11.6 per cent in Call of Duty 4 and a healthy 15.8 per cent boost for Crysis.

Given the lacklustre overclocking capabilities of our graphics card, we're sure these figures would be even more impressive with a different graphics card. It's well worth pursuing this further yourself, as the results could be significantly better.

Conclusion

It doesn't take long to get your head around the basics of overclocking. After all, there are only a few settings to adjust at any one time. The results are real, though, and can easily make the difference between an unplayable 19fps in a game and an acceptably smooth 25fps.