Graphics card upgrade: your options explained

8th May 2011 | 09:00

Graphics card upgrade: your options explained

Complete guide to buying a new graphics card

Graphics card upgrade guide

The graphics card is the racehorse of your PC components stable. It's a high-value add-in board that's traditionally done one thing and one thing only: let you play games with all the latest graphical wizardry.

Increasingly though, the graphics card is becoming far more than just a gamer's luxury. With architecture improving year on year, 3D graphics aren't the only thing your discrete GPU can do.

It can now be used to enhance your web browsing experience and enjoyment of high-definition media, let you explore your creative side with enhancements for productivity software and even help cure terminal diseases through projects like Folding@home.

So as well as producing some stunning visuals, your graphics card can also help save lives.

In the last decade, GPUs have been following in the footsteps of the CPU market, with increased core and thread counts. Speed in MHz or GHz is no longer the only measure of a chip's power, whether it's a GPU or a CPU.

What counts now is the number of cores, and how much data the chip can process at any one time. In CPU terms, the maximum on the desktop is six cores and 12 threads, and a full-fat 12 cores in the server space.

The top-end Nvidia GPU – the GeForce GTX 580 – has 512 CUDA (Compute Unified Device Architecture) cores. Meanwhile, the AMD Radeon HD 6970 has 1,536 shader processors, all of which are simple processors capable of taking on tasks such as video encoding, where some simple parallel processing is needed to enhance speed.

Nvidia was first to take this on with its CUDA cores, which let programmers write code in industry-standard languages such as C++. This code is run using all the shader processors (or CUDA cores) in Nvidia's GTX 8-series onwards.

Microsoft's latest update to its graphics API – DirectX 11, has done a similar thing with its Compute feature, which enables general purpose applications to run through a DirectX-capable GPU rather than taxing the processor.

If the GPU is becoming ever more powerful, why is there such doom and gloom around the discrete graphics card market? According to Intel and AMD, the future is fusion.

Are integrated graphics the next big step in the great graphics war?


There are many reasons to be upbeat about the future of discrete graphics cards. There isn't going to be a new games console release for another couple of years now, and the mid-range cards of today are far superior to anything the Xbox 360 or PS3 contain, so the PC is the platform to go for if you want to see the top releases looking their best.

Integrated graphics (the graphics processing power that traditionally comes with your processor chipset combination of CPU and motherboard) are catching up, though. They're changing as well – moving from the motherboard onto the CPU. All the big boys are getting involved.

First there was Intel and its Arrandale processors, which packaged a GPU and CPU on the same chip. Then came the company's Sandy Bridge, with its fully integrated processor graphics.

AMD has recently released its first Fusion board to the world, housing a tiny CPU and GPU setup – the first new CPU architecture we've seen from the company in years.

At this year's Consumer Electronics Show, held in Las Vegas in January, Nvidia announced Project Denver, its own collaboration with ARM to create a powerful desktop CPU with Nvidia's GPU architecture built right in. This may not shake up the high end of the discrete graphics market – after all, the latest 3D games are still going to need a power-hungry graphics card sitting in that PCI Express slot – but the value end of the market is going to change.

Processor graphics will be more than capable of coping with high definition video, encoding and casual gaming, so why would you choose to spend £50 on a separate card that will do the same job?

That said, times move quickly in the graphics card market, and tomorrow's £50 GPU will make processor graphics weep. AMD and Nvidia will be launching a slew of low-end cards to prop up their latest HD 6xxx and 5xx series respectively.

The high end will probably see the biggest battle. Nvidia's GTX 580 is currently top dog, but AMD is due to release its dual-GPU Antilles behemoth in the next few months, possibly at the CeBIT show in Germany. Details are scarce, but if AMD follows the example set by its previous dual-GPU releases, you can expect two Cayman Pro GPUs wired into one slice of AMD-red PCB.

HD 6950

Those are the chips powering the superlative Radeon HD 6950, and will make for one hell of a card.

Don't expect Nvidia to be keeping quiet, though. When we spoke with Tom Petersen, the company's Director of Technical Marketing, at the secretive preview of the GTX 580 last year, we asked if he expected to see a dual-GPU Fermi card any time soon.

He explained that, now the thermal issues seen in the first high-end Fermi card (the GTX 480) had been solved in the GTX 580 and GTX 570, there really wasn't a barrier any more.

So pretend to be surprised when Nvidia announces a GTX 595 just as AMD starts to get excited about its Antilles card.

Three top graphics card choices

Zotac GTX 580 AMP
Price: £480

Zotac gtx 580

On the basis that money is no object in your search for graphics perfection, you'll be hard-pressed to find a more impressive pixel-pusher than Zotac's recently launched, overclocked GTX 580 AMP.

This souped-up version of Nvidia's GPU is the fastest thing on two PCIe power cables. Based almost entirely on the first Fermi card, the GTX 480, it's undoubtedly what the brand wanted to release originally.

The GTX 480 had a cutdown version of its low-yielding GF 100, with one streaming microprocessor turned off. That meant a lowly 480 CUDA cores instead of the full 512 we were expecting.

The GTX 580 came out of nowhere last year with the full complement, plus nifty power and cooling advances. So it's quicker, cooler, quieter and far more power-efficient. In short, it's just better.

The AMP version is ever so slightly overclocked, but will also give a little more headroom should you wish to push it further. At these speeds though, you won't need to for a few years at least.

Verdict: 4.5/5

Asus GTX 460 Top 768MB
Price: £130

Asus gtx 460

We've already seen the stock GTX 460 768MB, and now it's the turn of the overclocked cards in the shape of Asus' GTX 460 768MB TOP edition.

The GTX 460 looks set to be the most successful iteration of the Fermi architecture that Nvidia has released to date. That's mainly thanks to a redesigned chip, still based on the same technology that made the GTX 480 such a blisteringly fast, and hot, card.

This new GF104 GPU is a far more streamlined chip compared to the fairly bestial GF100.

It still has the same basic premise running through it, but more cores have been squeezed into fewer streaming microprocessors (SMs) and more texture and special funtion units have been jammed in there too.

Verdict: 3.5/5

Read the full Asus GTX 460 Top 768MB review

Sapphire Radeon HD 6950
All round
Price: £228

HD 6950

AMD's Radeon HD 6950 is the must-have card of the moment, its price tag hitting the sweet spot in terms of cost/performance ratios.

The card is based on AMD's latest Cayman GPU, and with its redesigned approach to tessellation, offers some serious competition for the far more expensive GTX 570. It's also the only card under £250 that can take on the tessellation-heavy Metro 2033 at an eye-bleeding 2,560 x 1,600 resolution and still come out smiling.

The Cayman GPU's twin tessellation engines make the HD 6950 an excellent DirectX 11 card. On the DX 10 benchmarks it loses ground to the new GTX 560 Ti from Nvidia, but the AMD card has the better scores in the newest titles and comes with an impressive trick up its sleeve.

With a simple BIOS flash you can upgrade your HD 6950 and turn it into an HD 6970 – a £270 card – for free. That's not an overclock; it's unlocking dormant parts of the GPU and setting them free. That makes it the card of choice right now.

Verdict: 5/5

How to overclock your graphics card


With any sort of gaming, the biggest performance boost you can get is by making a change to your graphics card. However, that doesn't mean you need to kick your existing card into touch and dip your hand into your wallet to fund a quicker one.

Overclocking your graphics card is the quickest, cheapest and (most likely) easiest way to wring a little extra performance out of your current GPU. It was originally seen as a way to make older components competitive for longer, whereas it's now an expected consideration when you're choosing any new graphics card.

It's also not as dangerous as it once was; it's fairly difficult to brick a GPU with the simple overclocking you can do in Windows.

Generally speaking, you'll be lucky to get a 10 per cent increase in performance, but those precious few extra frames per second can mean the difference between almost unplayable choppiness and smooth, slick action.

To get started, all you need is a software tool like MSI's Afterburner, a graphics stress test such as Heaven 2.1 and a bit of patience. With a few cards, including the Radeon HD 6950 we've already talked about, it's possible to make some BIOS tweaks to garner a boost in performance.

The HD 6950, for example, runs the same GPU as the HD 6970. All that's different is that the chip was chosen to go in the lower-price card and has some features turned off. Normally, these changes are hard-wired out of the GPU, but AMD decided to implement the castration with software pincers only, making for easy reversal.

This is an extremely rare state of affairs though, and we haven't seen similar things happen in the GPU game for years.

Another way to improve things is by taking the more heavy-handed approach of adding a second GPU to the equation. Multi-GPU graphics have come on leaps and bounds in the last couple of years. Now we're seeing performance with a second card hit the 2x boost we'd always hoped for – and even more in some cases.

The difficulty is with the motherboard. You need one that supports multi-GPU and, unfortunately, that's a tougher, more expensive journey if you want to go down the Nvidia SLI route.

However, most boards will support AMD's CrossFire technology as standard on extra PCIe lanes, so that's becoming far more popular.

Easy overclocking

1. The setup

steo 1

MSI's Afterburner has an impressive hardware monitoring display. Detach this from the main console and it will give you a better view.

Start up the Heaven 2.1 benchmark in Windowed mode, at a lower resolution than your desktop, but with high settings. This will stress your GPU as you apply the overclock to help you judge stability. If there are no graphical glitches on-screen, the OC is stable.

2. The push

step 2

You'll need to approach the memory and GPU overclocking of your card separately to judge the maximum overclock on each. Start with the memory and push the slider up in 5MHz increments.

After each step, watch the Heaven benchmark closely for artefacts. Keep doing this until you see problems, then step back the OC until they go. Reset the memory slider. Repeat for the processor clock.

3. The stress

step 3

Once you've discovered the top overclock for the GPU and memory clocks, set both sliders to their maximums and watch the benchmark. You'll have to knock back the relevant sliders to create a stable OC.

Pixel-sized artefacts mean there's a memory problem, and bright colour blocks represent GPU issues. When there are no artefacts, your OC is stable. Now stress test it in fullscreen mode to make sure.


First published in PC Plus Issue 307. Read PC Plus on PC, Mac and iPad

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