Upgrade: Does DiRT 3 play better with six cores?

When Dirt 3 was released the developers pointed out that their advanced code took advantage of extra physical processing cores.  Putting this to the test, we decided to investigate this further, by comparing an AMD quad-core and hex-core processor, on the basis of an upgrade.

DiRT 3 was only released about a month or so ago but has received a lot of praise from gamers and reviewers across the globe.  It is the latest iteration of the Colin McRae Rally series, despite Codemasters dropping the Colin McRae branding.  It supports DirectX 11 which enhances detail and brings a number of other visual enhancements to the gaming experience.

We will be comparing the AMD Phenom II X6 1090T processor which is clocked at 3.2 GHz to the AMD Athlon II X4 635 processor which is clocked at 2.9 GHz.  To make the test as fair as possible we overclocked the Athlon II X4 635 processor to 3.2 GHz, keeping the clock speeds identical. We wanted to focus on real world CPU's today to show differences in upgrading to six cores.

As we weren't able to adjust the multiplier on the Athlon II 635 processor, we boosted the baseclock from 200 MHz to 221 MHz, giving us a final clock speed of 3215 MHz using the standard multiplier of 14.5x.  Please bear in mind that the Athlon X4 system has a slight advantage as the memory is overclocked a little when the baseclock is increased to 1774 MHz from the 1600Mhz of the Phenom X6 system. Additionally, there are some architectural differences between the processors so its not a purely scientific test, but as a topic of interest we thought it would be worth a look.

Moving onto the testing itself, we used exactly the same test system for the two CPUs.  We used the latest Crosshair V Formula motherboard from Asus combined with a reference AMD Radeon 6950 graphics card and 4GB (2x 2GB) of Kingston HyperX Genesis memory @ 1600 MHz.

The test system was built inside a Corsair Obsidian 650D case and was powered with a Thermaltake ToughPower XT 750W power supply.   Microsoft Windows 7 Home Premium (64-bit) was configured onto a Intel 320 Series 160 GB SSD for testing with all the latest drivers installed.

We used the graphics settings displayed in the screenshot below for testing.

When using the Phenom 1090T processor in our system there was a 14% performance increase over the similarly clocked Athlon 635 CPU, highlighting that the 2 additional physical cores are making a difference, with the level 3 cache playing a part also.  Some people still question whether there is really a need for six cores at the moment but this test shows that they do give you a performance bump. This is currently looking to be a good upgrade move and an indication of things to come.

KitGuru says: Having six cores may boost your gaming performance but we look forward to seeing how eight cores perform when Bulldozer is released!

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