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AMD Radeon HD 7790 Review - Sea Islands and Bonaire Make an Appearance

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Manufacturer: AMD

A New GPU with the Same DNA

When we talked with AMD recently about its leaked roadmap that insinuated that we would not see any new GPUs in 2013, they were adamant that other options would be made available to gamers but were coy about about saying when and to what degree.  As it turns out, today marks the release of the Radeon HD 7790, a completely new piece of silicon under the Sea Islands designation, that uses the same GCN (Graphics Core Next) architecture as the HD 7000-series / Southern Islands GPUs with a handful of tweaks and advantages from improved clock boosting with PowerTune to faster default memory clocks.

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To be clear, the Radeon HD 7790 is a completely new ASIC, not a rebranding of a currently available part, though the differences between the options are mostly in power routing and a reorganization of the GCN design found in Cape Verde and Pitcairn designs.  The code name for this particular GPU is Bonaire and it is one of several upcoming updates to the HD 7000 cards. 

Bonaire is built on the same 28nm TSMC process technology that all Southern Islands parts are built on and consists of 2.08 billion transistors in a 160 mm2 die.  Compared to the HD 7800 (Pitcairn) GPU at 212 mm2 and HD 7700 (Cape Verde) at 120 mm2, the chip for the HD 7790 falls right in between.  And while the die images above are likely not completely accurate, it definitely appears that AMD's engineers have reorganized the internals.

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Bonaire is built with 14 CUs (compute units) for a total stream processor count of 896, which places it closer to the performance level of the HD 7850 (1024 SPs) than it does the HD 7770 (640 SPs).  The new Sea Islands GPU includes the same dual tessellation engines of the higher end HD 7000s as well and a solid 128-bit memory bus that runs at 6.0 Gbps out the gate on the 1GB frame buffer.  The new memory controller is completely reworked in Bonaire and allows for a total memory bandwidth of 96 GB/s in comparison to the 72 GB/s of the HD 7770 and peaking theoretical compute performance at 1.79 TFLOPS.

The GPU clock rate is set at 1.0 GHz, but there is more on that later.

Continue reading our review of the Sapphire AMD Radeon HD 7790 1GB Bonaire GPU!!

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By far the biggest change on the HD 7790 is the updated version of PowerTune that includes a more granular version of boost to allow for more steps in discrete clock speeds and GPU voltage levels.  AMD promises that this version will allows for higher sustained engine clocks for more gaming performance while also being more power efficient, as well as being completely predictable. 

The graphic above represents the current PowerTune with Boost found in the HD 7970 GHz Edition and the HD 7950 with Boost cards on the market today.  The not-so-secret of that version of the technology was that there was truly only one additional step over the standard power management system. 

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Today's HD 7790 will be the first GPU to implement 8 discrete DPM states that the ASIC can switch between at a speed of 10ms.  Not all of these new states lie between the "high state" and the "boost state" though in comparison to the previous graphic, leaving us some questions as to the effectiveness of this version of PowerTune in the long run.  It does allow the GPU to use less power and use finer steps between the High and Boost states by not forcing the GPU to use one of only two voltage levels. 

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AMD did tell us that the "effective clock" will now be reported in the CCC as well as other overclocking and monitoring tools so we can actually see the clock rates change.  I am going to be revisiting PowerTune and its Boost changes in the near future but the fact is that without overclocking, the HD 7790 very rarely even enters anything other than the Boost state while gaming - a fact that AMD confirmed to us during early meetings about the product. 

Interestingly, AMD also changes the basics of the algorithm for boosting the clock speed, as it is now dependent on GPU load, current levels and a calculated, digital estimation of temperature.  Still, AMD is confident that every buyer will get the same exact GPU performance and alterations across the entire line of HD 7790s, unlike the promises from NVIDIA of slight variances of clock speeds in tradeoff for higher "typical" clocks. 

Again, more on this later - we don't yet have the right product to really test out AMD's updated technology.

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Here is the comparison of the HD 7790 with the HD 7770 and HD 7750, though the HD 7850 statistics are left out.  Obviously the HD 7790 is speced out better than the other HD 7700 parts, but the HD 7850 is only going to cost another $15-25 more than the new HD 7790 so it may be the more important comparison (it is included in our benchmarks).

Notice the 1.0 GHz clock rate listed here, without a designated "boost" clock.  How can you have PowerTune with Boost and not list a boost clock?  The truth is the GPU will basically ALWAYS be running at 1.0 GHz, the highest DPM state of the GPU.  That is why I feel that the explanation of boost technology is kind of lost on this product - there is no variance in the speeds you will see during gaming.

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For our testing AMD and Sapphire sent us a Dual-X overclocked model of the HD 7790, pushing the GPU clock rates up to 1.075 GHz and the memory speed from 6.0 GHz to 6.4 GHz - healthy boosts on both fronts. 

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The Radeon HD 7790 is fairly small card and only requires a single 6-pin ATX power connector to meet the TDP of 85 watts. 

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Front panels connections on the Sapphire card include a pair of DVI connections (one single, one dual link), a full size HDMI and a full size DisplayPort.  This is easily one of the best output configurations we have seen on an AMD HD 7000 card and mirrors the combinations that the GTX 600s tend to use.

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The back side of the board is pretty bare and it appears that Sapphire could have made this card even shorter if the needed to.  Maybe we'll see some really small SFF options using this new GPU?

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Finally, here is a slide of collected data on many of the partner cards releasing today or in the next week based on the HD 7790.  All of them are overclocked on either the GPU or memory clock, with most of them on BOTH, so hunt around if you are looking to pick up one of these new cards.

March 21, 2013 | 10:19 PM - Posted by John Doe (not verified)

I'd much rather take the rebate and shoot for this:

http://www.microcenter.com/product/397023/HD7850-DC2-2GD5-V2_AMD_Radeon_...

March 22, 2013 | 09:55 AM - Posted by MarkT (not verified)

If this was a 2gig card it would prolly beat the 7850? Im guessing on that.

March 22, 2013 | 01:38 PM - Posted by Ryan Shrout

I don't think so - the shader count difference is the main reason performance gap at 1080p.

March 22, 2013 | 10:14 AM - Posted by MarkT (not verified)

question: In both areas, Radeon graphics and A-series APUs, AMD does have some distinct advantages. Clarificiation?

March 22, 2013 | 01:40 PM - Posted by Ryan Shrout

On the APU side, AMD's edge comes with a higher performance integrated GPU and better parallel compute performance.

On the GPU side, AMD has better price/perf in many market segments, runs slightly more efficient at idle, etc.

March 22, 2013 | 05:39 PM - Posted by John Doe (not verified)

If you're doing single GPU, then 7970 will come in significantly cheaper than a 680 and beat it, but ONLY at STOCK because it has a higher stock clock (Ghz edition).

A 680 clocked over 1350 Mhz can and will blow a 7970 Ghz out of the water.

But it's pretty hard to hit 1400-1500 on stock cooler on a 680. The only cards that can easily do those speeds are the MSI 680 PE, Galaxy 680 White and the Sparkle Calibre 680.

March 23, 2013 | 10:48 AM - Posted by Ryan Shrout

Fair enough but this is a completely different class of card we are reviewing here.  

March 26, 2013 | 03:36 AM - Posted by Anon (not verified)

So the 7970 can't overclock.

OK.

March 26, 2013 | 11:22 PM - Posted by John Doe (not verified)

It can. Sigh.

The GHZ edition 7970 is nothing more than a PRE-OVERCLOCKED 7970, so it nowhere has as much headroom as a good 680 solution.

The 7970's aren't built as well or as well clocking as the top notch 680's, since they aren't as efficient.

Not to mention that AMD drivers are currently a complete and total mess.

That new 7990 which just popped out today may be a worth a wait.

March 23, 2013 | 04:26 AM - Posted by Tri Wahyudianto (not verified)

yes maybe 7790 is better price/performance than 650Ti, but i think nvidia PhysX got greater effect in gamer's eyes, or at least for me

so my conclusion is a draw, 7790 + never settle = 169 and 650Ti + PhysX = 149

plus in my country, AMD always get more dollar than in newegg, but Nvidia's price exactly same.

thank you for the review and simple, refreshing and new visual graphic

March 23, 2013 | 10:51 AM - Posted by Ryan Shrout

Thank you for the feedback!  I just don't tend to put much weight behind PhysX because it is used in so few games and when it is, I don't feel the effect is particularly interesting.  

March 23, 2013 | 12:49 PM - Posted by John Doe (not verified)

It depends entirely on how well PhysX is implemented in it.

Regardless, I agree that PhysX is nothing more than a pile of shit at it's current rate.

It will probably die once Unreal 3 Engine dies.

March 23, 2013 | 01:01 PM - Posted by Ryan Shrout

I just don't know how much more money NVIDIA is going to be willing to spend on it, considering none of the new consoles will ever use it.

March 24, 2013 | 08:44 AM - Posted by renz (not verified)

lol i heard rumors about unreal engine 4 will use PhysX as their physic engine. btw we might not see much about gpu accelerated physics from PhysX in the future but i don't think physx will die just like that. PhysX is a complete physic engine so they can license the tech for any developer that interested to use third party physic engine.

March 25, 2013 | 01:58 PM - Posted by aparsh335i (not verified)

Never Settle > PhysX

March 23, 2013 | 10:17 AM - Posted by Trey Long (not verified)

What happened to latency testing?

March 23, 2013 | 10:49 AM - Posted by Ryan Shrout

Stay tuned very shortly!!

March 23, 2013 | 05:22 PM - Posted by Wolvenmoon (not verified)

Luxmark?

March 23, 2013 | 05:51 PM - Posted by John Doe (not verified)

It's basically a 7770 on roids. It wouldn't perform all that well on Luxmark, which seems to depend and base the power it requires on shader strenght.

This card isn't as strong as a 7850 in the shader department, like nowhere is. It bases it's power on high clock frequencies.

If you want something to render, then that 7850 I linked to would do a much better job.

Also, this card is done on a 650-like PCB with many different capacitors, chokes, coils etc. all thrown across from whatever they had in stock. I'm not even sure how reliable this card would be on the long run.

That Asus 7850 DCII I linked to would be a much more superior choice, both in terms of power, build quality and longevity.

March 23, 2013 | 08:59 PM - Posted by K. Brent Church (not verified)

Any idea how this fairs against a GTX 460? Would it be enough of a jump to make the $150 worth it? I only game at 1080p and so far the 460 is holding up. GeForce Experience helps with some games very well and I don't have the really new titles to push it more. For that matter, I have two monitors, both hooked up to the 460. Would hooking up the second monitor to the my i5's 3570 Intel HD4000 graphics help with frame rates on the main monitor?

March 24, 2013 | 09:58 AM - Posted by renz (not verified)

it depends on how much performance jump that you can consider as an upgrade.

March 29, 2013 | 04:28 AM - Posted by rrr (not verified)

7790 is about on par with 6870.
460 (1GB 336 SP in particular) is on par with 6850, SE versions might be somewhat slower.

So it is one performance tier up at worst, one and a half tier at best.

April 16, 2013 | 01:43 PM - Posted by GTX460 (not verified)

I actually have the same question/problem and could really use some help. I only game at 1080p, and have a GTX 460 I bought for a new build in December 2010 (Core i7-950).
The card is holding up for me, I just finished FarCry3 a few weeks ago without complaints.
But the AMD deal for Bioshock Infinite and FC3 Blood Dragon, included with an HD 7790 for $160 has me scratching my head. I mean, I almost bought Bioshock two days ago for $59.99 on Steam. What to do????

March 24, 2013 | 09:21 AM - Posted by John Doe (not verified)

I'd just save up and get something real like this:

http://www.amazon.com/PowerColor-DisplayPort-PCI-Express-AX7870-2GBD5-2D...

March 25, 2013 | 01:57 PM - Posted by saneblane (not verified)

You are the first person I have seen to refer to the 7790 as Sea Islands. Is this confirm by Amd?,or is it a best guess situation.

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