Overclocking:
The Sapphire Radeon HD3870 X2 graphics card comes with both GPUs running at 825MHz and the 1GB of GDDR4 memory running at 901MHz. Considering that stand alone HD3870 cards can run at faster speeds, I was hopeful that this X2 version would have some room for improvement in both departments.
I only used the Catalyst Control Center's Overdrive tab for overclocking, and while it is a rather useful tool, it does prevent you from getting too crazy. The maximum allowable overclock on the GPU is 53MHz, which takes you to 878MHz. On the memory side of things you can go up 54MHz, which takes you to 955MHz. Without using a third party overclocking application, you're looking at a somewhat conservative boost of 6% maximum.
I started by working the GPU up slowly, testing for stability with every increase in frequency. Within no time the GPU was maxed out and still stable. I then returned the GPU to stock speed and did the same thing with the memory. It was also able to run at the maximum allowed by the Overdrive tab. Now that I had seen that they were both capable of running maxed out on their own, I set both sliders to the max and did a bit of testing.
We will cover the results for all tests in the next section of the review, but even this slight speed boost proved to be a worthwhile venture. For reference, this 6% overclock raised the total score for 3DMark06 by 544 Marks to 16090, and the average frame rates achieved in "Company of Heroes - Opposing Fronts" climbed by 2.1 fps to 53.2.
Testing:
A system with the following components was used to test the Sapphire Radeon HD3870 X2 1GB graphics card:
» Intel Core 2 Duo E6850 Dual Core processor running at 3375MHz (9x375MHz)
» OCZ Technology Vendetta CPU cooler
» ASUS P5K Pro P35 ATX motherboard
» Kingston HyperX PC-9200 2GB DDR2 dual channel memory running at 1200MHz, 5-5-5-15
» Maxtor MaxLine III 250GB SATA 3Gbps hard drive
» Tuniq Miniplant 950W power supply
All tests were conducted in Windows Vista Home Premium with all updates current as of early March 2008 (prior to SP1). In lieu of the driver's provided with the card, version 8.3 of the ATI Catalyst software suite was used.
For comparison purposes the following cards were used in this review...
» 1024MB Sapphire HD3870 X2
» 512MB ASUS EAH3870 TOP
» 256MB ASUS EAH3850 TOP
» 256MB Visiontek HD3850
The image below shows all of the cards being tested, and from left to right we have the Visiontek HD3850, the ASUS HD3850 TOP, the ASUS HD3870 TOP, and finally the Sapphire HD3870 X2. The Sapphire card is much longer than any of the other cards, so small form factor system owners should take a few measurements before deciding that one of these big boys is right for them.
The table below provides a side-by-side comparison of the key features and specifications for the four cards to be tested. The HD3870 X2 ranks second in terms of GPU and memory speed, but with twice as many GPUs and twice as much memory it might make up for that.
