Recently we've seen a flurry of ultra high-end graphics cards from both nVidia and AMD with the GTX590 and HD6990 respectively.
By inserting new models at the peak of the range the pricing has crept down slightly on the rest of the available cards meaning you can get a hell of a lot of performance for your pound. With the HD6850 available for around the £135 mark and the GTX550Ti around £115 the days of being unable to get more than an asthmatic wheeze out of a value card are long gone as both will provide decent performance for the outlay.
Appearing beneath the HD6850 in the AMD range the new kid on the Value block is the HD6790. In the same way that going big with high-end cards has diminishing returns, so the same is true at the lower end. Eventually continually cutting down performance to reach a budget will stop having a good card for the money and rather just leave you with something that might run Freecell.
So which camp does the HD6790 fall into? Is it a performance lunatic hiding under a reduced price tag, or one step too far?
The natural comparison for the HD6790 is the current Value card in the Radeon range, the HD6850. The HD6790 has 160 fewer Stream Processors, 8 fewer Texture Units and half the ROPs. This ends up giving us a slightly reduced Compute Performance and Texture Fillrate, but only around 55% of the Pixel Fillrate and Z/Stencil.
On paper at least it's not promising.
Our model of the HD6790 is an OEM version, so devoid of any stickers or fanciness. In this guise you can really see how uninteresting the reference cooler is. No vents or areas that will assist cooling in Crossfire.
The business end of the HD6790 follows the standard AMD pattern which enables Eyefinity. Dual DVI, HDMI and twin DisplayPort cover your output needs.
Power is provided by two PCIe 6-pin which should make sure the HD6790 gets all the power it could require even in overclocked trim.
Finally the only remotely noticeable feature is the standard red fan. We've been quite damning in our criticism of the noise that this generates normally, so we're interested to discover if it's much quieter now it wont have as much heat to shift.
Intel Core-i7 950 @ 4GHz
ASUS Rampage III Extreme
Muskin Joule 1200w
6GB Mushkin Redline
Windows 7 Ultimate x64
One of the primary reasons to buy a lower-end card is the overclocking potential and the performance that it will unlock.
The HD6790 was able to be pushed all the way from the default core speed of 840MHz all the way up to 985MHz on the GPU. Impressive overclocking performance.
Thanks to the greatly reduced capabilities of the underlying GPU, even with out overclock everything remains cool with the HD6790 maxing out at 69°C.
Of primary importance for us is that this performance doesn't come at the cost of fan noise, with the card being one of the quieter AMD ones we've tested recently.
3D Mark Vantage
At stock it clearly isn't a great performer in Vantage. Although the P score isn't bad we can't imagine there is anyone still running 1280x1024. With the detail pushed up it's a fair bit behind the slightly pricier HD6850. Overclocking it does unleash a fair bit of performance though and it's much close to the HD6850.
3D Mark 11
It's a different story in the shader intensive 3D Mark 11 though. Most modern games make good use of the DirectX shaders to give more realistic graphics and the HD6790 is really struggling. The first card we've tested to score beneath 1000 points in the X test. Even overclocking doesn't help much as the cut-down architecture is limiting things.
Unigine Heaven 0xAA
The Unigine Heaven Benchmark has been a happy hunting ground for AMD with their recent cards, but not today. Once again it's such a cut-down card that even with zero Anti-Aliasing the HD6790 just runs out of puff.
Understandably with Anti-Aliasing turned on things don't improve. We're not expecting miracles from a value card, but even compared to the slightly more expensive HD6850 it's a long way behind.
Alien vs Predator
AvP is a lot kinder. Although out of the box it struggles to pass the bare minimum 30 FPS average, at least with the overclock in place it has a little more get up and go.
Things are very similar in Crysis Warhead. Obviously for a low-end card we're running only at Gamer settings and zero Anti-Aliasing but still the HD6790 manages a healthy 40FPS. Despite only grabbing 4 more frames from the overclock the most important thing is the big leap in minimum frame-rate which helps reduce the stuttering as the card tries to keep up.
We did run in maxed Enthusiast mode but an average of 20FPS isn't desirable to anyone and if you wanted to run in those conditions you shouldn't be looking at such a basic graphics card in the first place.
Far Cry 2
By virtue of its older, less shader intensive, nature we'd expect Far Cry 2 to perform well on the HD6790 but it's actually the opposite with the scores as low as we've ever seen. Not very good.
With a single card Metro 2033 gives fairly standard results across the board. We're not too certain why but even the most powerful single GPU doesn't really force the issue. Thankfully for AMD this means the HD6790 becomes the little card that could here, only 10 FPS behind a stock GTX570.
We've always been a big fan of the lesser cards here at OC3D. They are cheap to buy and usually can be overclocked to give performance that you'd expect from a much more expensive card.The HD6870 in particular is one we love as it's great in a single-card form but runs with the best when in Crossfire.
So we had reasonably high hopes that the HD6790 would be right at the perfect place for a good value card that would overclock well and give lovely performance for those of us on a tight budget.
As it is the HD6790 is quite the opposite. Although in one or two tests it gives us fairly reasonable results, the reality is that it's just been trimmed and tweaked too much on the architectural side to allow some overclocking to bring it up to speed.
In fact the performance is such that it's really only a worthy purchase if you don't plan on doing much at all with it and only want something that is capable of giving you a desktop and playing the odd video. There however it comes undone again because there are a wealth of cards that are perfectly adequate for those tasks.
We're pretty sure you'd want to do some gaming on your latest purchase, and if you are on a budget you also want it to last a fair while as there will be a natural gap between upgrades. We can see absolutely no reason why you'd not save the extra 20-odd quid for a HD6850 which is a much higher performing card in a wealth of scenarios, and yet still wont break the bank.
All in all the HD6790 is a drop too far. It's not good enough or cheap enough to take sales away from any of the cards already stuffed into this sector of the market, not least AMDs own HD6850. With a price around £80 it would be a worthy investment, but as it stands it's a bit too pricey and a bit too slow.
Thanks to AMD for supplying the HD6790 for review. Discuss in our forums.