Double the fast: Palit HD 4870 X2 Review - PAGE 1

It must be a nice time to be an employee of ATI -- probably better of a time than it has been in some time now. With the latest generation of Radeons released, 'four' turned out to be the luckiest number: the HD 4850 and HD 4870 stacked up well against NVIDIA's new GTX 260 and GTX 280 cards, and won many gamers' hearts. Hopefully more than one bottle of champagne broke out when the first laudatory reviews of the HD 4850 and HD 4870 began to roll in.

The HD 4850 line offered unheralded levels of game performance for an affordable price of $200. For those looking for a bit more power, the HD 4870 brought buckets more of power to the table, for the still reasonably affordable price of $300. But -- of course, no matter how fast you get, you can always go faster, and there are always people willing to pony up the cash for the best they can get. 

Today we will be looking at what may prove to be the fastest single video card currently available today, the HD 4870 X2 (code-name: R700). The HD 4870 X2's introduction is perhaps not the best kept secret on Internet -- pretty much everybody assumed that ATI would follow a key maneuver in the game plan laid down with the HD 3xxx series, and come up with a new dual-GPU video card. Where NVIDIA usually brings out a sort of flagship dreadnought video card to launch a new series, ATI now takes a different approach. With the HD 4850, ATI's first move was for the market's jugular -- the 'performance' market segment, the $200 - $300 video card that appeals probably to a larger majority, than a smaller minority, of PC gamers because of the price. And now, after launching the HD 4870 and HD 4850, instead of devoting a bunch of resources on making a 'ultra-enthusiast' designation, top-of-the-line GPU that only addresses a relatively small consumer market, ATI decided to work with CrossFire and make the fastest video card in their arsenal a dual-GPU card, as they did with the HD 3870 X2.  

However, two important differences came with the HD 4870 X2 this time around. The first difference was that ATI released the HD 4870 X2 much quicker than they did the HD 3870 X2 -- remember, the HD4850 was only launched in late June. And secondly, while the HD 3870 X2 was a  successful product, it did little to differentiate itself from two HD 3870 cards running in CrossFire when it came to performance -- and often, two HD3870 cards sold for less than did one HD3870X2, because of the intervening time elapsed in its release. The second difference this time around is that the HD 4870 X2 has a new trick up its sleeve, called the sideport.

The sideport is a GPU-to-GPU CrossFire interconnect that should give the HD4870X2 an edge that the HD3870X2 did not have. For those of you that have had two or more video cards running in a CrossFire setup, you might have wondered how much data could be passed through the the flimsy and thin-looking CrossFire bridge(s). The answer is, relatively speaking, not that much. While the CrossFire bridges were capable of passing .9 GB/second, the new sideport interconnect allows for the theoretical limit of 5 GB/second, which, according to AMD, should increase a HD4870X2 performance over a two HD4870 cards CrossFire'd by %10-%15. 

Facilitating this greater GPU-to-GPU digital dialogue is a PCI Express 2.0 Switch 'ExpressLane' bridge chip made by PLX Technology. Between this chip, the greater bandwidth allowed by PCIe version 2.0, and the CrossFire bridge, where the HD3870X2 had 6.8 GB/second of interconnect bandwidth, the HD4870X2 is capable of up to 21.8 GB/second (at least theoretically.)

From the perspective of raw computational horsepower, the power of HD4870X2 is immense. Let's do a bit of math here: one 55nm-process HD4870 RV770 GPU has 800 stream processors. Built in accordance with ATI's TeraScale graphics engine design, the GPU manages to pack 956 million transistors onto a die 266mm². Okay -- that is one HD4870, so what kind of binary-pushing plateaus could we reach with the HD4870X2? AMD proclaims that the HD4870X2 is capable of 2.4 TeraFLOPS -- which is almost insane. That's 24,000,000,000,000 floating point operations in one single second. That's a whole lot of FLOPS. If you had a HD4870X2 in the mid-1990's, KGB spies would be trying to kill you for it.

The best part of all this is that all of this fantastic technology and engineering has been applied to one primary purpose: to deliver some very, very serious gaming sessions.

Let's take a closer look at this video card...

Update: August 12th: The numbers for our Call of Juarez benchmark, posted last night, seemed off so we re-tested those results, and yes, they were off. We are currently in the process of re-testing all of the benchmarks, to make certain that no other numbers are off. Meanwhile, the Call of Juarez results have been removed. We apologize for this error. If more problems are found we will let you know, and if need be, we will change our conclusion accordingly. Thank you for your understanding. (And no, this was not a conspiracy.)