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The Asus EAH3870X2 1GB TOP is one of the largest and heaviest video cards I've had the opportunity to handle in my tenure as Neoseeker's video card review guy.

Coming in just a few millimeters shy of the length of a Asus EN8800 GTX, the 37 centimeter long EAH3870X2 has a larger dual fan, double-slot cooling solution on it. The fans are bolted in above each GPU. Each GPU has a seperate heatsink; and unusually, both heatsinks are made of different metals: one heatsink is copper, and one is aluminum. This non-reference cooling solution from Asus is the only one currently available with two fans.

Both fans of the EAH3870X2 also have Republic of Gamers stickers on them. The 'Republic of Gamers' tag line is usually associated with Asus' high-end motherboards. But if there was one card to put these stickers on to, it would rightfully be the EAH3870X2. 

The HD 3870 X2 cards were named using logic, not marketing spiel -- thankfully that X2 doesn't stand for 'X'treme squared! The X2 simply means HD 3870 times two. Which is what we have here: two RV670 55nm GPU's coming through the glory of CrossFire to make a RV680. Snuggled between each GPU is a PCIe 1.1 bridge chip. While PCIe 2.0 bridge chips are around, they don't really offer any real-world performance increases beyond what a PCIe1.1 bridge chip can offer, due to the fact that even the fastest of today's cards do not suffer from bandwidth saturation with PCIe 1.1. Besides which, AMD probably already had a bunch of 1.1 bridge chips kicking around the warehouses, immediately available for use, which helps cut down productions costs.

Anyways: the CrossFire is hardwired to always be 'ON', so the EAH3870 X2 requires no fiddling with drivers to enable full performance. For many people, after installing the card, they may forget altogether that they have two GPU's processing polygons for them, instead of one. On the subject of CrossFire, what about CrossFireX? If you've been following your tech reading, CrossFireX is the new generation of CrossFire coming from ATI that'll allow up to 4 physical cards running on high-end motherboards, in a Spider platform. So, you may be wondering: what if you put 4 HD 3870 X2's in a rig? Would you some sort of 8 GPU craziness going on? Well, no such luck -- the HD 3870 X2 only has one CrossFire interconnect, so you'll have to be content with only four GPUs. Sigh. I know, I know: only four. Sarcasm aside, that is one more benefit of the EAH3870X2: if you have a common two PCIe slot CrossFire friendly motherboard you'll be able to run a pair of these cards for 4 GPU's worth of game power, once the CrossFireX drivers are released.     

The dual nature of the EAH3870X2 also goes beyond just the GPU. Each GPU has a 512 MB of GDDR3 to work with, through a 256-bit memory bus -- the same found on the HD 3870. These combine to give the EAH3870X2 1GB of memory overall, and a 512-bit memory interface when you consider both working in tandem. Further showing that the HD3870X2 is a 'double HD 3870', is that has exactly twice the amount of stream processors (640), texture units (32), and ROPS (32). In a perfect world, where magical drivers exist, the HD3870X2 would deliver double the performance of a HD 3870, but in the real world, this just isn't the case. A single-GPU video card with the same number of stream processors, texture units, ROPS and same clock speeds would probably out-perform a dual GPU video card with a similar configuration. But the benches will let us know for sure.    

Speaking of clock speeds, for the reference model HD 3870 X2 the core clock has been increased from the HD 3870's 775 by 50 MHz, to 825 MHz; while the HD 3870 X2 memory clock has gone down to 1.8 GHz from the 2.25 GHz default memory clock of the HD 3870. Fans of Asus hardware will probably know that the TOP branding means that the card is factory overclocked, and this once again the case with the EAH3870X2 TOP. The core clock is set to 851 MHz, while the .8ns GDDR3 memory clock sits pretty at 1.9 GHz. In addition to the Top Overclocking Performance, this Asus card differs from the non-TOP version by also having that superior dual-fan cooler (which should be help with further overclocking), and additionally also having four DVI connectors (with HDMI output support), plus a HDTV out. This is the first video card that I've laid eyes on that has four DVI connectors and it really helps this TOP edition stand out from the pack.  

In addition, the EAH3870X2 has some other 3xxx series common features, such as UVD for improved HD playback, DirectX10.1 support, a Tessellation unit, and ATI PowerPlay.

To power this beast of a card, your going to need at least two six-pin power connectors. If you want to overclock the EAH3870X2, you will need a six-pin connector, and a eight-pin power connector as well. Asus put another nice small touch on the card here: the power connectors are angled up on the EAH3870X2, unlike the reference board design, where they stick out of the card perpendicularly.