Radeon HD 4890 vs GeForce GTX 275

ATI Radeon HD 4890 1GB

Manufacturer: AMD
UK Price (as reviewed): Typical price £220 (inc. VAT)
US Price (as reviewed): Typical price $249.99 (ex. Tax)

Nvidia GeForce GTX 275 896MB

Manufacturer: Nvidia
UK Price (as reviewed): £220 (inc. VAT)
US Price (as reviewed): MSRP $249 (ex. Tax)

Introducing the new competition from ATI and Nvidia

It’s been a while since we’ve seen ATI and Nvidia scrap it out with two comparably priced cards launching on the same day, but this month they’re right back at it. The Radeon HD 4890 is best seen as an overclocked 1GB Radeon HD 4870 – the architecture is the same and it’s still built using a 55nm process, but ATI has slightly stretched the design to widen the internal copper interconnects and put a crucial few more atoms of silicon between the transistors. The stretched design reduces transistor power leakage and strengthens signal integrity, which in turn allows the chip to run at higher frequencies.

Stock clocked Radeon HD 4890s ship with a GPU clocked at 850MHz, which is 100MHz faster than the Radeon HD 4870's engine clock, and the Qimonda GDDR5 memory is now running at 975MHz (3.9GHz effective) rather than 900MHz (3.6GHz effective). ATI claims that the RV790 GPU can be easily overclocked to 1GHz and beyond (with watercooling), however we're dubious about how much the stock cooler can take.

With the new GeForce GTX 275, Nvidia is sticking to its strategy of modifying its 55nm GT200 GPU to suit whichever price point it fancies hitting. The GTX 275 therefore has 240 stream processors and a 448-bit memory interface. This means that the GTX 275 is very similar to the GPUs used in the GeForce GTX 295, differing only in clock speeds.

The twin GPUs in the GTX 295 operate at 576MHz, compared to the GTX 275 which is clocked at 633MHz and likewise the stream processors of the GTX 295 GPUs run at 1,242MHz, rather than 1,404MHz in the GTX 275. Memory is still limited to GDDR3, and the GTX 275 has 896MB of it running at 1,134MHz (2,268MHz effective) rather than the 999MHz (1,998MHz effective) GDDR3 memory of the GTX 295. Why is the GTX 275 GPU faster than those of the GTX 295? Because it has a dedicated dual slot heatsink for just one GPU, it has two 6-pin power connectors all to itself and it has more PCB space for better power hardware underneath as well.

In terms of price, neither of these new cards will break the bank. Both cards cost roughly £220, give or take a few pounds. However, Palit has produced an own-design version of the GTX 275 for £199.99 inc. VAT on launch day. As we were given a reference card to test, all of the following data cannot be applied to this Palit card, and so any price/performance comparisons we make in this article will be made on the prices given for reference design GTX 275 cards.

To see how the two new GPUs stack up in the line-ups of the two graphics companies, we've knocked together the handy specs table above, and we've also got some details for a few partner cards over the next two pages. Unfortunately Nvidia was less "ready" than AMD at this launch, playing role of the reactionary party and only a reference card was available to us in time for the launch. In comparison, no less than five AMD partners got us Radeon HD 4890 cards for launch day, however one had an issue with its artwork (no, not a "wardrobe malfunction").

Nvidia GeForce GTX 275

Core Clock: 633MHz
Shader Clock: 1,404MHz
Memory Clock: 2,268MHz (effective)
Memory: 896MB GDDR3

You'd be easily mistaken in thinking Nvidia's GeForce GTX 275 was a GeForce GTX 285 without knowing the difference or seeing a sticker. Both use two 6-pin power adapters, both are the same length and both are very black. The only difference is what appears to be an optimised (cost reduced) PCB and two less DRAM chips, because of the smaller bus and total footprint.

Click to enlarge

The cooler has been changed to closer match the 9800 GTX GeForce GTS 250, as a single moulded piece of plastic, instead of the metal grill-shape on the outside edge. Like all current GT200 derivatives, sound over HDMI still requires an S/PDIF pass through cable near the power cables.

Sapphire ATI Radeon HD 4850 X2 2GB

Manufacturer: $339.99 (ex. Tax)
UK Price (as reviewed): £259.97 (inc. VAT)
US Price (as reviewed): $339.99 (ex. Tax)

Core Clock: 625MHz
Memory Clock: 1,986MHz
Memory: 2,048MB GDDR3
Warranty: Two years (parts and labour)

We had a brief look at Sapphire's ATI Radeon HD 4850 X2 in November when the card launched, but at the time there was no official driver support from AMD – the company simply provided us with a pre-release hotfix driver that wasn't available for download. This driver had some issues where performance dived through the floor and then we learned that official AMD support wasn't forthcoming until at least Catalyst 9.1.

With Sapphire eager to get ahead of the game though, it has recently released a version of the Catalyst 8.12 WHQL driver with a modified INF file that enables support for the 4850 X2. The driver is WHQL certified and available for download direct from the company's website – this isn't quite official support from AMD, but it's as close as we're going to get for now and it's therefore time to get down and dirty with Sapphire's rather interesting dual-GPU monster. Read on to find out how it gets on...

At the time of our initial preview of the card, a number of ATI board partners had come to us to say that they were planning to release their own Radeon HD 4850 X2s very soon – so far, none of those promises have rung true and Sapphire has maintained its exclusivity in the market. At the same time, the card's price has dropped a bit since November – it's now available for under £260, which is over 15 percent less than the original £300 asking price.

The card has the same number of stream processors as the Radeon HD 4870 X2, which means there are two 'full' RV770 GPUs under the heatsink each with 160 five-way shader units (making a total of 1,600 stream processors over the two GPUs). The clock speeds are exactly the same as a single Radeon HD 4850 as well – the core is clocked at 625MHz, while the GDDR3 memory runs at 1,986MHz (effective).

Unlike the standard Radeon HD 4850, Sapphire has included 1GB of memory per GPU on this Radeon HD 4850 X2 instead of the 512MB on a standard 4850. There is another, cheaper version of the card with 1GB of GDDR3 (512MB per GPU) – that retails for about £240 to £250 though, so we'd definitely recommend spending that little bit more on the 2GB variant based on the comparisons we've done between single 512MB and 1GB Radeon HD 4850 (and 4870) cards so far.

There are a couple of 80mm fans attached to an aluminium shroud with Sapphire's branding emblazoned onto it. The two RV770 cores are cooled by large aluminium heatsinks with a copper insert above each GPU core, while a third heatsink sits atop the PCI-Express switch positioned between the two GPUs. In addition, there are another couple of heatsinks on the power circuitry (one on the front and one on the back) that makes sure the PWMs are kept cool. Normally, we'd be a little concerned about a relatively tall heatsink placed on the back of the card covering additional power circuitry, but because of the card's length, it shouldn't cause any problems.

Sadly, the card cannot be classed as quiet – far from it, in fact – and we think that's partly down to the decision to use fairly a basic aluminium/copper hybrid heatsink design on the GPU cores. It would have been more efficient to use a heatpipe design, but sadly there doesn't look to be enough room for that. And there are some components that would get in the way of a single heatsink design covering all three chips.

Sapphire has chosen not to use the Radeon HD 4870 X2's reference design PCB – probably because of the different traces required from the GPU(s) to memory – and has instead opted for its own design. It is longer than the Radeon HD 4870 X2 reference design (283mm compared to 267mm), which means that it will not fit in every chassis out there – be sure to check that you have enough room for the card to fit in your case.

Unlike the 4870 X2, the 4850 X2's memory resides only on the top side of the card – they're cooled with simple L-shaped aluminium cooling plates secured with three push pins. Moreover, the power circuit is also quite different to the Radeon HD 4870 X2's as well – most of the components are located down near to the dual power connectors (one 8-pin and one 6-pin) and is a seven phase circuit covered mostly by the pair of aluminium heatsinks – one on the front and one on the back.

There are a few components nestled in between the GPUs though (which prevent the single heatsink design we just mentioned) and are comprised of a pair of phases with each including a single choke and three MOSFETs. These appear to control power to the PLX PCI-Express switch, but it's not 100 percent clear based on the traces visible on the surface of the PCB

Click to enlarge

On the PCI bracket, Sapphire has done what Asus did with the Radeon HD 3870 X2 – it has implemented four dual-link DVI connectors that will certainly please multi-monitor lovers because you can not only run CrossFire, but also connect up to four high-resolution digital displays. The bracket is rounded off with an analogue TV-out connector – Sapphire has included composite and component adapters in the bundle.

And while we're talking about the bundle, Sapphire has included a pretty good selection of items in the box. In addition to the aforementioned cables, there is a DVI-to-HDMI dongle, a DVI-to-VGA connector, two supplementary power connectors, a CrossFire connector and a selection of software that includes Cyberlink PowerDVD, DVD Suite and 3DMark Vantage.

Warranty & Support

The Sapphire ATI Radeon HD 4850 X2 comes complete with a two-year warranty that includes cover for parts and labour. During the first year of the product’s life, your point of contact should be the retailer. However, if you’re having problems getting hold of the retailer (or the retailer goes out of business), you should contact Sapphire’s support team directly. During the second year of the warranty period, you should talk directly with Sapphire.

Overclocking

Considering how low the operating temperatures are on Sapphire's ATI Radeon HD 4850 X2, we expected the card to overclock fairly well and we weren't disappointed.

We managed to increase the core speed from its default 625MHz up to 696MHz - an eleven percent improvement - while the memory was quite happy running up at 2,300MHz (effective). This represented a 16 percent increase in memory bandwidth.

What was disappointing was the fact we couldn't use our favourite RivaTuner software - the latest version wouldn't allow us to adjust clock frequencies - but we suspect this will be fixed before long, as it should be just a case of adding the card's deviceID into the application. We instead used the OverDrive utility inside the Catalyst Control Center to achieve this overclock.

In terms of performance, we saw our Far Cry 2 frame rates increase by just under 10 percent at 1,920 x 1,200 4xAA 16xAF. This means that our overclocked Radeon HD 4850 X2 was just 6.6 percent slower than a stock Radeon HD 4870 X2 at these settings - that's pretty impressive with all things considered.

Final Thoughts...

We’re very much in two minds about Sapphire’s ATI Radeon HD 4850 X2 2GB, because although the card is generally a better performer than Nvidia’s recently-released GeForce GTX 285, there are a number of issues that we can’t ignore. The first is the fact that this is a dual-GPU card and AMD’s support for it hasn’t been as forthcoming as we would have hoped.

Even today, going to AMD’s driver page looking for updated drivers for the Radeon HD 4850 X2 is a failure – that’s where we downloaded our drivers from originally and our attempts to install them didn’t yield positive results. Instead, it resulted in frustration – there is still no official support for this card through the usual channel, even though it’s plastered right the way through AMD’s internal marketing slides. And this is almost three months after the card was originally released!

Of course, we have been able to get drivers through Sapphire’s own driver portal – but that’s not the first place anyone is going to look and it also relies on Sapphire keeping its own driver page updated with modified ATI drivers. If we were to poll readers on where they’d expect to get drivers for an ATI Radeon HD 4850 X2 from, the majority would no doubt say ATI or AMD – we don’t understand why, almost three months after the card was released, we still can’t do that.

To me, there’s something clearly wrong with AMD’s monthly driver strategy and this hasn’t been creeping up – it’s something I’ve pointed out for a long time, but usually in relation to multi-GPU profile support in new games and not getting the latest products working. Catalyst 9.1 hasn’t been released yet, but it’s the driver where official 4850 X2 support has been promised and we’re hoping that is still the case. If it’s not, then I am not sure what to think.

The other major disappointment for us with the Sapphire Radeon HD 4850 X2 is the noise it makes – it’s far too loud for a modern graphics card and we have moved away from the whiney fans of the early naughties. Sadly, the two fans on the Sapphire Radeon HD 4850 X2 just make us want to jam a couple of pencils in them to shut them up – they verge on offensively loud if we’re honest and to add insult to injury, there’s no fan speed control available in any of the monitoring software we’ve tried so far.

Despite these flaws, the Sapphire Radeon HD 4850 X2 does deliver a generally better gaming experience than Nvidia’s more expensive GeForce GTX 285. The cheapest we have been able to find the 285 for is around £300, including VAT, which makes it £40 more expensive than the 4850 X2. That makes the decision difficult and while we’d typically recommend a single GPU solution almost every time (especially in light of what we’ve described above), the price difference makes it an awkward choice – the GTX 285 is 15 percent more expensive and it’s slower in four of the seven games we’ve tested here.

Frankly, the Sapphire Radeon HD 4850 X2 is too loud for a modern gaming system, driver support isn’t where we’d like it and the GeForce GTX 285 is too expensive. In light of this, we don’t believe there is a perfect choice in this segment of the market and it opens up a window of opportunity for the manufacturer who wants it the most. Right now, we’d avoid this part of the market altogether and either go higher or lower depending on your screen size and budget elasticity.