AMD Radeon HD 7770 review
The first two graphics cards in AMD's new range, the "Tahiti"-codenamed Radeon HD 7950 and Radeon HD 7970, blew us away with their performance but, at £350 and £450 respectively, they're incredibly expensive.
The HD 7770 is the top of AMD's new mid-range "Cape Verde" graphics card line. It’s really a follow-up to one of our favourite mid-range graphics cards, the Radeon HD 5770, and AMD makes a big deal in its literature about how the HD 5770 is the "most successful DirectX 11 GPU to date as chosen by gamers", with a claimed 28 per cent of the market.
Unlike the Radeon HD 6770, which was essentially a tweaked HD 5770 with identical performance, the HD 7770 is a brand new graphics card based on a new 28nm GPU - the 5770's GPU was based on a 40nm process. The new card has 640 stream processors compared to the HD 5770's 800 and its 1GB of GDDR5 memory runs at 1.125GHz instead of 1.2GHz, but it makes up for this with a 1GHz instead of 850MHz core clock speed.
The card is slightly shorter than the HD 5770 at 211mm, so you shouldn't have a problem fitting it in most cases, and it needs a single 6-pin PCI Express power connector. On the rear are a single DVI, one HDMI and two Mini DisplayPort plugs, so you can run three monitors if you have a DisplayPort model or using a £17 active DisplayPort adaptor.
Judging by the specifications, we didn't feel the HD 7770 was going to be much of a step up from the HD 5770/HD 6770. However, the new card definitely showed a significant performance boost in our Dirt 3 test. At 1,920 x 1,080 with Ultra detail and 4x anti-aliasing, we saw a very smooth 41.3fps from the HD 7770, compared to 35.7fps from the older card - not a huge increase, but enough to stop the frame rate dipping below the 30fps mark during hectic scenes.
We had less luck in our Crysis 2 benchmark, where the HD 7770's results were almost identical to the HD 5770's - at 1,920 x 1,080 with Ultra detail, we saw just 15.4fps, which is essentially the same as the HD 5770's 15fps. Even when we turned down the detail to Very High the new card only had 25.9fps compared the HD 5770's 24.7 - Crysis 2's hugely high-resolution textures seemed to be troubling the cards' small 1GB of memory.
Turning back to Dirt 3 for our three-monitor Eyefinity test, the HD 7770's high clock speeds saved the day; at 5,760 x 1,080 with High detail and 4x anti-aliasing, we saw 36.6fps, compared to a not-quite-smooth 29.5fps from the HD 5770.
We tried overclocking the HD 7770 with the Catalyst Control Center's Overdrive utility, but it seems to be clocked almost as far as it can go; we managed to overclock the core to 1.1GHz, but this only increased our Dirt 3 Eyefinity score to 38.5fps.
UK pricing for the card has just been announced; the HD 7770 will be £120 inc VAT from www.aria.co.uk, which is around £10 more than the current price for the HD 5770. However, the HD 6770, which has identical performance to the HD 5770, is currently just £86. The HD 7770 may be around 15 per cent faster, but it's also about 30 per cent more expensive than the HD 6770. It's a fine mid-range graphics card and once prices have settled down it may well be our favourite card, but in the meantime we recommend picking up its bargain predecessor.
|Interface||PCI Express x16|
|Slots taken up||2|
|Graphics Processor||AMD Radeon HD 7770|
|GPU clock speed||1.00GHz|
|Architecture||640 stream processors|
|Power leads required||1x 6-pin PCI Express|