AMD ATI Radeon HD 4870 X2

Item: AMD ATI Radeon HD 4870 X2
Author: Tim Smalley

Written by Tim Smalley

August 13, 2008 | 08:06

Tags: #4870 #card #crossfire #hd #multi-gpu #performance #r700 #radeon #review #rv770 #sideport #x2

Companies: #amd #ati #test

Conclusions

The easiest thing to say here would be that AMD achieved its aim in making the world’s fastest graphics card with the Radeon HD 4870 X2 – a title that it hasn’t held for almost longer than I dare think about. Nvidia has had a pretty easy ride since the launch of the GeForce 8800 GTX in late 2006 and it now faces its toughest test for almost two years.

But if I left it at that, I don’t think I’d be telling the full story. The 4870 X2, in many respects, is similar to the Radeon HD 3870 X2 from an implementation standpoint, but there is considerably better GPU technology behind the newer card and that means when you find a scenario for the card to scale well, you’ll see some simply mind-blowing frame rates.

Making a multi-GPU graphics card isn’t, by any stretch of the imagination, an elegant way to create the highest-performing single graphics card because, with the way the current technology from both AMD and Nvidia works, there’s a lot of faith being put on the driver team. Frankly, I’m not comfortable with that because performance can range anywhere from chart-toppingly brilliant to decidedly midrange depending on how good the drivers are.

Even worse is the fact that multi-GPU scaling isn’t a given and even if the driver team puts the time into optimising a particular title, there could be a scenario where the game is written in such a way that it doesn’t easily take advantage of multiple GPUs, but it clearly benefits from more GPU horsepower. This is a concern for me if I’m going to be spending upwards of £300 on a high-end graphics card.

It’s also why we’re approaching a point where both CrossFire and SLI technology need to evolve far beyond what we have today—especially if the technology is going to be used to occupy the ultra high-end space where consumers are spending a lot of money and therefore have high expectations. We need driver transparency and we need multiple-GPUs to be able to access the same memory pool – the current technology is incredibly wasteful and diminishing returns really kick in fast when you start putting more than two GPUs in a system.

Architectures are unified these days and in most of today’s shader heavy games, you can really achieve some almost linear performance gains just from increasing the number of execution units. Yet with multi-GPU technology, we don’t see anything near to linear gains with even just two GPUs and to me that means there’s a problem with the underlying technology.

One big, fast, single GPU will always be more attractive to me until we reach the holy grail for multi-GPU technology, no matter how transparent cards like the Radeon HD 4870 X2 are – they’re just not transparent enough. And when I say that, the Radeon HD 4870 X2 is the most transparent multi-GPU graphics card we’ve seen to date because, like the 3870 X2, multi-monitor fanatics aren’t crucified just because they have a craving for the fastest graphics cards on the planet.

Performance scaling also seems a bit better across the board too, thanks to some of the innovations introduced in the new PCI-Express switch, but again I’m concerned about the attitude towards Sideport technology. Quite often in the past, ATI has come up with some great ideas that never end up being used – and it’s looking like Sideport may fall into that category too. We hope it doesn’t, but right now I’m not going to hold my breath in anticipation.

Final Thoughts

AMD has done a great job with the Radeon HD 4870 X2 and it has snatched the crown for the fastest graphics card in the world back from Nvidia in the process. Like we’ve said though, it’s not all rosy and there are drawbacks associated with buying a Radeon HD 4870 X2, just like there are with any other multi-GPU configuration. As long as you’re prepared to accept them, then the Radeon HD 4870 X2 is well worth considering if you’ve got that kind of cash to throw around.

The GeForce GTX 280’s new price point makes it seem like an attractive buy as well, with cards starting anywhere from about £260-275 including VAT. If anything though, the Radeon HD 4870 X2 makes a single Radeon HD 4870 or GeForce GTX 260 look like better options today because it’s almost as if there’s too much horsepower on tap here with AMD’s new flagship card.

Right now, the Radeon HD 4870 X2’s most impressive performance gains can really only be seen at the lofty resolution of 2,560 x 1,600 or with high levels of Anti Aliasing at 1,920 x 1,200 – at lower resolutions, or lower levels of AA, the gains just aren’t there at all. However, given that there’s a slew of new (and hopefully more graphically intense) games about to hit the shelves before Christmas, picking up a Radeon HD 4870 X2 if you’ve got a 24-inch widescreen doesn’t seem like such a bad idea – you can play today’s games with stupidly high levels of AA and hopefully tomorrow’s games at native resolution with no big compromises to image quality.