ASUS EAH3870X2 review
Author: Luka Rakamaric
Date: 08 Mar 2008

Almost 10 months ago we saw ATI release HD2900XT, its first DX10 card, and after the first numbers from benchmarks we saw something that never happened before. ATI released a card that even didn't try to win the flagship position. They have surrendered to NVIDIA dominance employed by the G80 GPU in the 8800 series cards. Instead they aimed their product to a lower price segment, although realistically it should have cost more than $399, especially because it required a complicated cooling solution and power management. Even then, the card couldn’t compete with the intended rivals, namely 8800GTS 640 MB. Almost six months later, AMD successfully transferred its production to 55 nm, which made the heat dissipation of their new product much more bearable, but it did not enable them to release a high end card. The HD3870 was somewhere on the level of HD2900XT, compensating for the reduced bus width with higher clocks. It still lost to the slightly more expensive 8800GT. Since they couldn’t introduce a real high end GPU, they decided to make the next best thing, and that’s making a 2 GPU card. The 3870 X2 was born.


When we first got the HD2900XT card we were really amazed a t its weight, because its 2 heatpipe cooler was completely copper. The subsequent versions had a 3 heatpipe design which was even heavier. The 3870 X2 is a significantly longer card, and is heavier, but you will not be amazed since the subjective weight is less due to its size. The giant long cooler is covering the card from end to front, and beneath are not two but three large chips. The two are a pair of R680 GPUs already seen in single 3870 cards, and the third is the 48 lane PCI-E chip. Each of the GPUs are connected to it via 16 lanes (32 total), and the remaining 16 are going to the PCI-E connector on the bottom of the card. There is no support for PCI-E 2.0 here, but in reality it is not necessary for GPUs with this level of processing power. Two GPUs naturally require a lot of processing power, and this card is equipped with one 6 pin and one 8 pin connector. When you take off the cooler, you can see that the 3870 X2 is packed with electronic components all over the PCB, especially on back side where power is distributed. In reality, the card would work just fine with ‘only’ two 6 pin connectors, since it uses 55 nm GPUs. The most important thing is the usage of a 12 layer PCB which enables less signal noise and interference, and consequently higher GPU clocks. Much to our surprise, especially after NVIDIA’s 7950GX2 experience, the core clocks on the X2 are higher than on the plain 3870 card. That is probably why there is an 8 pin connector. The card, like the 2900XT works just fine with only 2x 6 pin plugged in, but you won’t get overclocking capabilities from Catalyst Control Panel. Although ATI Overdrive is disabled, you can still use ATI tool with 2x 6 pin connectors. 

Unfortunately, to keep the prices low, 3870 X2 gets rid of 1125 MHz GDDR4 memory and instead uses 900 MHz GDDR3.  The memory capacity is 1 GB, but since the GPUs can’t share memory, each of the GPUs has only 512 MB at its disposal. In theory, this combination should lose to 3870 in Crossfire because of the memory clock which is significantly lower. However, the core clock has gone up from 775 to 825 MHz, so it should compensate for some of the performance loss, especially in lower resolutions.

Test setup
- Intel Core 2 Quad Extreme QX9650 333x9, 3.0 GHz
- Gigabyte X38-DQ6
- OCZ Platinum XTC PC2-8000, 2 x 1GB, 4-4-4-12 @ 800 MHz
- Western Digital Raptor X 150 GB
- PC Power & Cooling Turbo Cool 1KW-SR

We benchmarked 2 resolutions, 1920x1200 and 1680x1050, which are the most common on today’s 22 and 24 inch LCD screens.