We may be preparing for an imminent explosion of new graphics chips, but until then there are some juicy prices to be had on existing graphics chips.
The Sapphire AMD Radeon HD 6790 is a very modestly priced card that hovers at around the magic £100 mark, yet offers the performance to give some very playable game framerates. Perhaps we shouldn’t be too surprised at this – despite slotting in at the high end of the 6700 series, it uses similar technology to the considerably more expensive 6800-series cards.
The 6790’s chip is essentially a pared-down version of the processor employed by the AMD Radeon HD 6850 and 6870. It sacrifices a good number of the stream processors: the 6790 offers 800, against the 960 and 1120 delivered by the 6850 and 6870 respectively. In truth, though, 800 stream processors will be more than enough for the majority of today’s games.
Indeed, many an nVidia graphics-processing chip makes do with far fewer of these. You also see a drop in the texture units, with the 6790’s count of 40 down somewhat on the 48/56 of those two 6800-series cards. Again, though, 40 is more or less what you should expect at this price point.
Elsewhere, the Sapphire AMD Radeon HD 6790 is also pleasingly well specified. The 256-bit memory interface is fairly wide, and you’ll have to spend well over twice as much to improve here. You can add to that some capable clock speeds – the 6790 has a core clock of 840MHz, with a memory clock of 1050MHz (which increases to an effective 4200MHz when the quad-rate DDR is taken into account).
Indeed, its memory bandwidth of 134.4GBps beats the figure of 128GBps offered by the more expensive Sapphire 6850 in our chart. With these specs, we should have a card that offers plenty of raw speed.
The Sapphire AMD Radeon HD 6790’s memory bandwidth might better the 6850’s figure, but the 6790 is still unable to keep up in a full-bore gaming context.
Its general performance is slightly below that of nVidia’s successful GTX 460 series.
In Crysis, for example, the 6790 hit 24.8 and 19.4fps at 1680x1050 and 1900x1200 resolutions. The nVidia GTX 460 with 768MB of memory, in reply, notched up 26.9 and 20.8fps, while the 6850 keeps significantly clear with 27.8 and 22.9fps respectively.
In Stalker: Call of Pripyat, the 6790’s figures of 29.8 and 24.9fps were several frames away from the 460’s 34.6 and 27.3fps, while the 6850 posted figures of 36.1 and 29.3fps.
In BattleForge, the 6790’s 25.7 and 20.1fps slip behind the 460’s 27.1 and 21.8fps, and very noticeably trail the 6850’s figures of 32.2 and 25.9fps.
The Sapphire 6790 comes with four ports in all – two DVI (one of them single-link, one dual-link), HDMI 1.4a and a DisplayPort. It needs two 6-pin connectors for power.
The quoted TDP of 115 watt is very decent, with the 6850 specified at about 127W and the 6870 needing up to 151W.
Sound levels were modest too, with the 6790 significantly audible only at times of full load from a particularly intensive game.