AMD Radeon HD 7870 GHz Edition & HD 7850 Review - Conclusions
The Radeon HD 7800 series is not a sizable improvement over the HD 6900 it replaces (from a price and spec point), and I think AMD realizes this. Over the last two generations they have expanded the x900 family to hold their flagship SKUs, and beef up the "performance" family (the x800 numbering) to include enthusiast class specs like a 2GB frame buffer. Even in their press materials, AMD is targeting users who purchased the Radeon 5870 two years ago, and are looking to an upgrade.
The Radeon HD 7870 GHz Edition and the HD 7850 solid performing cards - they just don't perform significantly better than their previous counterparts. It appears that for this iteration, AMD has deployed a "tick tock" model similar to the one Intel uses in its CPUs. The Radeon HD 7800 family does everything that the HD 6900 did, and does it (a bit) better. The real improvement is that it does it with far less power, and produces far less noise and heat - the results of the shrink to the 28nm process. The lack of significant performance improvements isn't necessarily a bad thing, and it's not something that can be expected in every generation from any company. Improving efficiencies is always good, and lays the groundwork for future improvements. The Radeon HD 6900 family was a significant improvement over the previous generation, and the Radeon HD 7800 improves the performance slightly from there.
If you're in the market for a new card (and if you own a 5000-series, you should be), then the Radeon 7800 family is a great performer, is a good value, and is very efficient at what it does. However, if you already have a 6000-series card, and are looking to upgrade, then you're going to have to jump price points to get significant improvement. If you have a Radeon HD 6800 card, then the HD 7900 will make you happy with its faster shaders, more shaders and more VRAM - you'll just need to spend about $100 more than you did on your last card. However, I think the increase in VRAM alone is worth it.
If you already have a Radeon HD 6900 series card, you'll need to shell out an extra $150 - $200 (beyond your last purchase price) to pick up a Radeon HD 7900 series to see any real improvement. Problem here is, the Radeon HD 7900 just might be overkill for you. And, you may be better served picking up a second 6900 card and going CrossFire.
Final Thoughts
We've had a look at all the single-GPU cards from AMD that I would consider in the "gaming" class. Anything below the Radeon HD 7700 family isn't really feasible for gaming. As this wraps up the bulk of our coverage on the Radeon HD 7000 series, I'm going to use this opportunity to provide my view on the whole line.
HTPC / SFF Users - The Radeon HD 7750 is your card. It pulls 30fps in many of our tests - at full settings, 4xAA and 16xAF. It could certainly pull 30fps or greater in many games with a few tweaks to the graphical settings. The card is small, efficient and quiet. It's low power draw means it doesn't need any external power and is being released in a few silent/fanless options. There is simply no reason to look any lower for a SFF or HTPC GPU.
Casual Widescreen Gamers - The Radeon HD 7770 GHz Edition isn't a bad card, but it just doesn't knock my socks off. Performance wise, it generally comes in just at or below the Radeon HD 6850. You may be better served by finding a Radeon HD 6850 on the cheap.
Dedicated Widescreen Gamers - The Radeon HD 7800 series offers good performance and a 2GB frame buffer (providing some future proofing). You can hit 60fps in almost all the games we tested, with little to no tweaking off of max settings. If you play on a single screen, and you're looking at a 7900-class card, take this advice... Save some money, on the card and pick up a couple of extra monitors to dip your toes in the Eyefinity pool. The Radeon HD 7800 series will provide you excellent (60fps) widescreen performance, and will give you a playable (30fps) Eyefinity experience in a wide selection of games.
Eyefinity Gamers - In the past I've been on the fence about needing 2GB of VRAM for Eyefinity. My first reaction to the launch of the Radeon HD 5870 was, "Eyefinity users need 2GB - it's that simple. ATI should have launched with a 2GB option, especially for those EF users runing 5760x1200." A few months later with the Radeon HD 5870 Eyefinity6 launch I said, "Make no mistake about it - 2GB of VRAM is not needed to play any game today in 3x1 Eyefinity. However, you won't be able to do it at max settings and consistently hit 60fps. You will have to reduce quality, sometimes to the point of virtually abandoning the DX11 code path and feature set all together."
Come forward ~18 months, and my mind is made up. You need 2GB of VRAM. Games have advanced. Features such as tessellation, HDAO, soft shadows and motion blur (not to mention good old AA) are putting more and more strain on your frame buffer. We're even at a point were 2GB of VRAM is needed to run a title at 1080p with 2xAA (Total War: Shogun 2). If you're at all serious about Eyefinity, you need a card with 2GB. So, the Radeon HD 7800 family is your starting point. Should you upgrade to the 3GB Radeon HD 7900 series?
The 3GB frame buffer and increased shaders offers a large improvement over the Radeon HD 6900 series in Eyefinity. Put a pair of them together and you have the biggest, baddest Eyefinity rig - bar none. Problem is that a pair of Radeon HD 7900 cards will cost you a grand.
Hardcore Eyefinity Users - A pair of Radeon HD 7900 series cards is a force to be reckoned with. Problem is they are expensive. The impending Radeon HD 7990 will certainly be cheaper than a pair of Radeon HD 7950's. If you want a single card solution, the 3GB Radeon HD 7900 will give you the best performance and help future proof you (and you can add a 2nd card once prices drop). If you're willing to pay for two cards, I would wait for the dual-GPU offering to make your decision.