Welcome to another AMD-releases-new-architecture review. Hopefully this one will go a bit better than the last one. Bulldozer was a disappointment to many. While I still hold it’s a solid CPU for the price point AMD set (but not current over-inflated retail prices), it definitely wasn’t the jump over Thuban everyone wanted it to be.

Enter Southern Islands and Graphics Core Next (GCN), a fundamental change to AMD’s approach to graphics processing. Will it struggle like AMD’s last fundamental change or will it rise above and be crowned the new king of graphics cores? Let’s find out, shall we?

Specifications, Features, Cooling & Power Consumption

This will be a bit shorter than you’re used to. We have the full info going over the architecture in detail and I’d love nothing more than to pontificate on its virtues, but unfortunately we’ve had very little lead time for this review. Being right before Christmas and, you know, having a family doesn’t lead to excessively detailed reviews when you only have a piece of hardware and info for six days (including one to type the review).

Getting right to it, there are going to be three iterations of the Southern Islands product line. All of them use GCN. The GPU we’ll be looking at today is code-named “Tahiti”, the highest-end Southern Islands part. The two to come in the future are “Pitcairn” and “Cape Verde”.

Graphics Core Next, or GCN is AMD’s latest and greatest GPU architecture. It is rated as PCI-e Gen3 (which comes with its own set of issues as you’ll see later), is produced on a 28 nm process and has advanced power management. For a superb comparison on how AMD’s GCN compares to its former VLIW4 architecture that, frankly, I just didn’t have time to type in the time between getting this info and now, check out this piece at Anandtech.

Eyefinity 2.0 comes with a new monitor orientation option that’s not necessarily practical but interesting to have (how many people have room for 5 x 1 landscape monitors?). New bezel compensation is coming down the road – ETA Feb. 2012, they will support bezel compensation across different-sized monitors.

They’re also introducing Eyefinity with HD3D. You’ll probably need some insane GPU power to produce 3D at very high resolutions, but they’re laying the foundation for the future.

They are also pushing the computing ability of this GPU, which should be quite a bit stronger than their former VLIW4 Cayman architecture. With such a short lead time, we’ve chosen to focus on how this thing will bench and run games, but down the road we’ll look at how it computes, especially with [email protected]

Here we have quick specs and features overview. The HD 7970 has 2048 stream processors. AMD calculates this GPU as having over 3.5 TeraFlops of computing power, which eclipses its 6970 predecessor. It also comes with 3 GB of 384-bit GDDR5 RAM – and the ability to use up to six monitors, which you’ll need to take advantage of all that video RAM.

For features, it comes native with four outputs – one DVI, one HDMI and two mini-DisplayPort. Yes, that’s only four outputs, but AMD is partnering with manufacturers and will be coming out with a splitter that plugs into one of those mini-DP outputs and will allow you full use of your six-monitor potential.

Like the HD 6970 before it, the HD 7970 also has a dual BIOS switch, with one protected stock BIOS and another for you to flash as you see fit. I was on pins and needles when I flashed a GTX 580 to get some more voltage control because there was no coming back if I messed it up. This makes that process worry-free. Now all we need is something to control voltage, which doesn’t exist yet!

The cooler is reported as having an improved fan design – larger, which will produce higher CFM and be quieter. Larger? Check. Higher CFM? Probably. Quieter? Um…it’s a squirrel cage fan in a GPU. They can only get so quiet. While CCC does keep the fan under control and you can barely hear it when benchmarking and gaming (wait until that voltage control I mentioned…), when you crank it up you’ll know it’s there. So will your family and your dog if they’re in the same room.

The heatsink definitely does a good job though, even when running quietly under CCC control. As with previous reviews, for temperature testing the fan was set at 75%, which is moderately loud, but not enough to drive you out of the room; it’s reasonable for gaming use. Temperatures were measured and normalized to 25 °C ambient temperature.

GPU: 6970 6990 X580 7970 Temp Idle: 33 °C 38 °C 29 °C 31 °C Temp Load: 51 °C 69 °C 57 °C 61 °C

It’s not the coolest GPU on the block, but does manage to be close to the Sparkle X580, which has an aftermarket Arctic cooler affixed from the factory. While it’s not as cool running as the HD 6970, it’s also much more powerful, so you’re sacrificing some degrees in exchange for performance, which is an acceptable trade-off for most overclockers.

As far as fan noise, it’s reasonable. Squirrel cage fans are always going to be loud when you ramp them up to four thousand or so RPM. I’ll never understand the people that always complain about loud squirrel cage fans on GPUs. Aren’t you used to it yet? Do you think physics is going to change all-of-a-sudden?

The thing is, when running games and benchmarks even overclocked the fan barely had to spin up to keep temps reasonable. So while it is definitely loud if you manually set it to 75 or 100%, if you let CCC control it, you might hear it but it won’t be anywhere near loud.

AMD introduced PowerTune with the HD 6900 series, where you can give up to 20% more power than stock to give your GPU some breathing room without actually considering it ‘voltage’ control. You can also turn it down 20% if you feel the urge.

PowerTune served us well for this GPU, for without it there would have been no added current capacity at all. Hopefully MSI (Afterburner) or Sapphire (TRIXX) will release updated versions of their software soon so we can show you what this thing can do with a little extra juice.

From sipping power at idle to loaded power efficiency, AMD is pushing power consumption heavily. Their GPUs have progressively dropped off to using almost zero power at idle. Now, this GPU will remain in the ‘normal’ range when it engages your screensaver (mine is ‘blank’) but will slip into ‘Long Idle’ when it powers the monitor down, reducing your GPU’s power sipping to a mere 3 W.

So, what does that translate to in real-world use? Idle wattage to make even the greenest gamer proud. These numbers are total system wattage as read via a Kill-a-Watt from the wall as we don’t have the capability of measuring the GPU wattage directly.

GPU: 6970 X580 6990 7970 Idle: 97 W 118 W 112 W 89 W GPU Load: 315 W 443 W 496 W 352 W GPU & CPU Load 371 W 496 W 557 W 408 W

When the GPU drops into Long Idle, the HD 7970’s idle wattage goes down ~6W, from 89 W to 83 W. That isn’t reflected in the chart because I didn’t test the other cards there to see if they had any improvement when they shut the monitor off. What’s even better about this Long Idle feature is when using CrossFireX. Until they are needed, your extra GPUs will stay powered down in the Long Idle position, sipping a mere 3W each. So until you engage a load that needs them you can have three more HD 7970s in your box pulling only nine additional watts. That’s quite impressive.

When the GPU is loaded it comes in above the HD 6970, but almost a full 100 W below the GTX 580, which isn’t too shabby at all. Considering the performance, this is one efficient GPU. 28 nm shrouded in strong power management looks good on AMD.

AMD is also practically begging you to overclock this GPU (though it’s still not covered under warranty of course). Stock speed on these is 925 MHz. They seem to think 1 GHz is not going to be too hard. We’ll find out soon enough – the new version of CCC goes up to 1125 MHz, if the GPU can make it that far.

The comparison between the HD 6970 and HD 7970 is not really much of a comparison. The HD 6970 wasn’t top dog when it came out and did not beat the already-king-of-the-hill GTX 580. It is a strong GPU and priced perfectly for its target market. It also scales very well in CrossFireX, easily reaching 85-90% improvement over a single card. It was not, however, the best single GPU. That title resided with NVIDIA. We’ll see later whether AMD has stolen the champion belt.

The specifications have been improved significantly. The slide before said the GPU has been calculated as having over 3.5 TeraFlops of computing power and this one shows just what ‘over’ means, stating 3.79 TFLOPS. The HD 7970 comes with the same number of ROPS, 32 more texture units and 512 additional stream processors.

It clocks in at 925 MHz core speed, 45 MHz more than its predecessor. Memory clock speed remains the same, but it has more bandwidth available due to the 384-bit wide memory interface (over the previous generation’s 256-bit).

As mentioned, it is produced on a 28 nm process and weighs in at a very hefty 4.31 billion transistors. We’ll have to assume that’s accurate and it’s not edited down by, oh, about 0.8 billion or so like Bulldozer. {Cough.} It also does all of this with a 250 W power rating identical to the HD 6970, which is impressive in itself and is due in no small part to said 28 mm process.

The Card

AMD has updated the look of their GPUs again and these look even better than last generation. They’re glossy red and black, so it’s a minor pain to photograph, but the look is quite stunning. See for yourself!

By now you know once it starts taking photos, my camera doesn’t like to stop. If you want to see a bunch more photos, feel free to click through.

The PCB is black (contrary to some leaked photos I’ve seen out there with red PCB), cleanly manufactured with neat soldering throughout.

Along with the identical 250 W TDP comes identical power connectors – one 8-pin and one 6-pin PCI-e connectors. On the right you can see the dual BIOS switch. It’s small and slightly recessed so the chances of accidentally tripping it are very slim. There are dual crossfire connectors for hooking up other GPUs.

Of course, it’s always fun to compare generations. The PCB is very nearly the same length as the 6970. The photo on the left looks shorter only because the cooler slopes on the end (as you can see above on the left). Turning them over shows they are very close to the same length. Surprisingly they did away with the backplate. I actually liked that feature as it kept components on the back of the PCB nice and cool.

I liked the prior generation’s looks, but they’ve done better this time around with a more streamlined, less boxy appearance. Though it’s not easy to photograph, the HD7970’s glossy sheen looks good and I actually prefer it to the matte black reference HD 6970 design.

Please accept my apologies for the lack of bare card photos. We were barred from removing the cooler prior to testing due to the proprietary thermal interface material and the slim post-testing time was spent compiling results and writing.

Test Systems

There are unfortunately two test setups involved when testing this GPU. Our editor splat went to the AMD tech briefing on this GPU in Austin, TX earlier this month and they understandably mistakenly shipped it to him. The stock benches were run on the same setup as all other benches in the charts you’ll see below (consisting of an i7 2600K at stock and DDR3-2133 memory). The overclocked HD 7970 results were not.

Unfortunately splat’s motherboard doesn’t like him any more and refuses to overclock, so the GPU was shipped to me (plus I have three monitors for Eyefinity). The only drawback is that the HD 7970 does not function in my P8P67 WS Revolution. That is the only socket 1155 motherboard in my posession. You can see our dilemma.

Because we had six days to work on this, we did the best we could for our readers. I took the Sandy Bridge-E socket 2011 system and hampered it to conform to the test parameters, running with four cores + HT active, dual channel DDR3-2133 RAM at stock i7 2600K speeds. Clock-for-clock, the two systems should be as nearly identical as you can make them. After testing, benchmarks between them all came very close to one another. There was one exception to the rule – 3DMark 11 just loves SNB-E for some reason. Aside from that they were all basically within margin-of-error similarity.

I’m hoping ASUS will be able to address this with a UEFI update. This is the PCI-e Gen. 3 specification problem I mentioned above. They are working on it and assuming it’s addressed, I’ll either verify the numbers are the same or correct them if necessary. For now, just note that we did the best we could in the time allotted; the difference, if any, will be minor

Overclocking

This card clocks like a champ. The only sort of voltage ‘control’ available to us was AMD’s PowerTune, which added +20% of…something. What that is I’m still not certain; doubtful it’s 20% core voltage, as that would get really hot, really quickly.

Author’s Note: Just to clarify, that is a tongue-in-cheek response to not knowing precisely how PowerTune affects voltages on the card. I do fully understand PowerTune adjusts the card’s P-states to allow it to operate at max TDP constantly. The question is how that translates to voltage adjustment, which we can’t know for sure.

Regardless, that 20% allowed us to take this GPU all the way to the maximum available clocks in Catalyst Control Center. Interestingly, where memory clocking wasn’t the 6970’s strongest area, the HD 7970 seems to enjoy overclocking there too.

Without batting an eye, the HD 7970 clocked right up to a completely stable 1125 MHz core speed and 1575 MHz memory speed. I can’t wait to get voltage control on these things. If it does that at stock, imagine what we can do with some more voltage available!

As an interesting side note, with a reduced-capability SNB-E system and only overclocking the GPU, that score would be third place on HWBot for 3DMark 11 – Extreme. It’s not popular like the Performance test, so there isn’t a lot of competition there, but it’s amusing how easily the HD7970 beats out the other results. If this is how it’s going to perform in our benchmarks and gaming tests, we’re in for a treat.

Performance

We’ll measure two categories of performance – 3D Benchmarking and Gaming.

3DMark Benchmarks

3DMark03 is old. Other members of our staff practically beg me to get rid of it, but despite its obsolescence this old thing still does a great job of measuring GPU horsepower. It scales as it should with GPU power and even multiple GPUs, assuming CPU overclocks (or lack thereof) remain the same.

The stock HD 7970 just edging out an overclocked GTX 580. When overclocked, it even takes out a stock HD 6990. We’re off to a great start so far.

Up next is 3DMark06; it’s a newer benchmark, which is strongly bound by CPU clocks but does show some scaling.

Very interesting. 06 goes the other way, with the GTX 580 winning out. Overclocking the cards yields very little improvement thanks to the aforementioned CPU-bound issues. It seems the GTX 580 is a bit stronger with DirectX 9. The 7970 definitely shows a fair bit of improvement over the previous generation. I’m honestly not sure what happened with the HD 6970 IceQ here as I didn’t review that one.

Moving up another DirectX level, we have DX10-based 3DMark Vantage. This one loves some CPU as well but still scales well with GPU power.

Back on top here. The stock HD 7970 beat the stock GTX 580 and they maintained a similar margin overclocked. Again, when overclocked the HD 7970 outdoes its dual-GPU cousin 6990.

Focus more on the stock results here. We see the stock HD 7970 beats the stock GTX 580 by almost 5%. The overclocked number is heavily skewed by the LGA 2011 platform we mentioned earlier, hence the ** by the result. Regardless of platform, scoring 9123 in 3DMark 11 with a single GPU is quite impressive.

Last in the benchmarking section is HWBot’s Heaven benchmark. This is more of a game benchmark than others in this section as it tests the Heaven game engine, but it’s scored like a benchmark.

Again the HD 7970 struts its stuff, with the stock result beating the overclocked GTX 580. Overclocked doesn’t catch up to the HD 6990, but does completely separate itself from the rest of the field.

Gaming Performance

Gaming is, of course, why a lot of overclockers become overclockers in the first place. You need every bit of extra FPS you can get, right??

The first game we’ll see is HAWX 2. This one is getting a bit long in the tooth, but we have comparison numbers so we might as well have a look, no?

This one was an interesting way to start, with the HD 7970 showing no improvement over its predecessor and getting beaten by the GTX 580 handily. I actually had this one rerun to ensure the numbers were accurate, and indeed they are. Regardless, truthfully, who needs 200 FPS when 160 is just fine?

The GTX 580 shows it has some life left in this game. Only the HD 6990 beat it out. The HD 7970 definitely improved over the HD 6970, but it didn’t take top spot for Dirt 2. Same deal as HAWX 2 though; these obviously don’t take a ton of horsepower to run, so what’s 124 FPS when you’re already at 110?

Stalker takes a bit more GPU intestinal fortitude than Dirt 2, making use of strong MSAA and Tessellation. We’ve chosen the most difficult of the four tests to present.

Computing heavy workloads is where this card really struts its stuff. Stock results come in very close to an overclocked GTX 580 and the HD 6990. Overclocked, it beats them both!

Up next is two iterations of Aliens vs. Predator DirectX 11 Benchmark, one with the default benchmark settings and the other with everything cranked up as high as it will go.

Only the HD 6990 beats the HD 7970 here. Everything else falls by the wayside. Overclocking it just increases the distance with which it beats the competition.

The GTX 580 and HD 7970 are a little closer here with more power needed to compete. Even so, the HD 7970 stock beats the overclocked GTX 580, then runs away overclocked.

Last up is the newest addition to our game lineup – Battlefield 3. It was run with the testing procedure outlined in our Battlefield 3 GPU Performance and Eyefinity Experience article.

Battlefield 3 is a strong test of GPU ability. As you can see it makes a single HD 6970 cry a little bit, but a GTX 580 can handle it nicely. What it can’t do is handle it as nicely as the HD 7970 can. The HD 7970 handily beats an overclocked GTX 580 and trounces it when overclocked. It even approaches SLI GTX 580s and the HD 6990. This is certainly one powerful new GPU!

Eyefinity Testing

With the ability for a single GPU card to run six monitors, Eyefinity is obviously a strong focus for AMD with the HD 7970. Thus, we connected up three monitors and tested all of the games in Eyefinity for you. This was a tri-monitor Eyefinity setup with three 1080p displays in landscape for a total resolution of 5760 x 1080.

Stalker, Hawx 2 & Dirt 2 are all graphed together.

These titles definitely look great on the HD 7970. It beat the HD 6990 at stock and even more so overclocked.

In Aliens vs. Predator the HD 6990 managed to stay on top, but after overclocking the HD 7970, it barely did so. This thing is a beast, coming very close to the previous generation dual-GPU card.

Another close matchup here, with the overclocked HD 7970 actually beating out the stock HD 6990. It even gets very close to matching the overclocked HD 6990, with a higher minimum FPS.

This GPU is amazing in its ability to keep up with the HD 6990 at such high resolutions. Frankly, before testing I didn’t think it would be able to keep up with that, but the HD 7970 even surpassed it when overclocked!

Putting Some Horsepower Behind The 7970

Of course, what fun is an Overclockers review without putting some strong CPU power behind the latest and greatest GPU? In this case, I unhindered the i7 3960X back to its 6-core/12-thread, quad-channel RAM goodness and clocked it to 5050 MHz. Then I cranked the GPU as far as it would go and ran 3DMark 06, Vantage and 11.

This managed to beat my previous personal best on a Sparkle X580. To get there before, I flashed the X580’s BIOS to allow greater voltage control and ran using the LoD (Level of Detail) turned down to max out the score. This just took overclocking with CCC. This is definitely a strong showing.

Now, Vantage is a completely different story. This score is a new best for our team, beating Miahallen’s very strong score by over 3000 points. He was using liquid nitrogen on the CPU and GPU too; this is with water on the CPU and stock cooling on the GPU.

This 3DMark 11 score – not too far short of 10,000 on a single stock-cooled GPU – is also a new team best, beating, coincidentally, another of Miahallen’s score (but only by 12 points)…I sense a crosshair on my back!

With stellar results like this, these things are going to lead to quite a voracious 3D benchmarking competition!

Final Thoughts & Conclusion

This review really surprised me. I expected it to be better than the HD 6970 but not to the level of the HD 6990. I had hoped it would beat the GTX 580, but didn’t have a clue by how much it would do so.

Instead, we see a GPU that is tantamount to parity with the dual-GPU beast HD 6990 and one that, for the most part, leaves the GTX 580 squarely in its dust. When it comes to strong computing power required for MSAA and Tessellation, it separates itself even farther (look at the Stalker and Battlefield 3 results!).

It seems to falter slightly with excessively high FPS games (such as Dirt 2 and HAWX 2…do you really need over 100 FPS? …over 200?) and, apparently, DirectX 9 as we see via 3DMark06. How many people currently play DirectX 9 games again? I’ll go with slim to none. Those that do will just have to make due with 150FPS instead of 200 FPS. Think you can handle that?

Back to heavy-duty graphics computations, go look at those Eyefinity results again. If the HD 7970 isn’t beating the HD 6990 at stock, it’s getting pretty darn close when overclocked. That was the one thing that surprised me the most. I figured at 1080p we’d see a close battle between the two, but when you put three monitors on the HD 7970 it would have to show some weakness. I figured wrong.

Of course a main concern will be how much this GPU costs. Unless I’m mistaken it is the first publicly available PCI-e 3.0 GPU, so there’s one thing to make it more expensive. Then you have the fact that it beats out the GTX 580, making it the most powerful single GPU on the planet. Any guesses where this will end up?

Ok, enough suspense. AMD is putting this card at an MSRP of $549, with expected availability on January 9, 2012. That’s about $50 higher than your average GTX 580 with 1.5 GB of RAM. What’s really interesting is that, if you narrow down Newegg results to show only 3 GB models of GTX 580, not one of them is cheaper than $549. Zotac comes close, with an out of stock model for $555, but the others are EVGA and start at $590, going up from there.

Retailers will surely tack on an early-adopter premium, but if they somehow miraculously release at their MSRP, the GTX 580 is going to need a price drop before long. Of course, NVIDIA is supposed to release its new Kepler architecture in 2012. AMD has beat them to the punch, and upped the ante. In some areas, even an overclocked GTX 580 can’t match the new HD 7970 beast at stock. 2012 just got very interesting for GPUs.

AMD has taken back the hill. It’s your move NVIDIA.

– Jeremy Vaughan (hokiealumnus)