AMD Radeon HD 7970 Review: 28nm And Graphics Core Next, Together As One
by Ryan Smith on December 22, 2011 12:00 AM EST- Posted in
- GPUs
- AMD
- Radeon
- ATI
- Radeon HD 7000
Tahiti: The First Direct3D 11.1 GPU
One of the many changes coming in Windows 8 next year will be the next iteration of Direct3D, which will be Direct3D 11.1. More so than any other version of Direct3D so far, D3D11.1 is best summed up as a housekeeping release. There will be some new features, but compared to even past point releases such as 10.1 and 9c it’s a small release that’s going to be focusing more on improving the API itself – particularly interoperability with SoC GPUs for Windows 8 – than it will be about introducing new features. This is largely a consequence of the growing length of time for all matters of development hardware and software. By the time Windows 8 ships Direct3D 11 will be 3 years old, but these days that’s shorter than the development period for some AAA games. Direct3D 11/11.1 will continue to be the current Windows 3D API for quite some time to come.
With regards to backward compatibility in D3D11.1, there’s one new feature in particular that requires new hardware to support it: Target Independent Rasterization. As a result AMD’s existing D3D11 GPUs cannot fully support D3D11.1, thereby making Tahiti the first D3D 11.1 GPU to be released. In practice this means that the hardware is once again ahead of the API, even more so than what we saw with G80 + D3D10 or Cypress (5870) + D3D11 since D3D11.1 isn’t due to arrive for roughly another year. For the time being Tahiti’s hardware supports it but AMD won’t enable this functionality until the future – the first driver with D3D11.1 support will be a beta driver for Windows 8, which we expect we’ll see for the Windows 8 beta next year.
So what does D3D11.1 bring to the table? The biggest end user feature is going to be the formalization of Stereo 3D support into the D3D API. Currently S3D is achieved by either partially going around D3D to present a quad buffer to games and applications that directly support S3D, or in the case of driver/middleware enhancement manipulating the rendering process itself to get the desired results. Formalizing S3D won’t remove the need for middleware to enable S3D on games that choose not to implement it, but for games that do choose to directly implement it such as Deus Ex, it will now be possible to do this through Direct3D.
S3D related sales have never been particularly spectacular, and no doubt the fragmentation of the market is partially to blame, so this may be the push in the right direction that the S3D market needs, if the wider consumer base is ready to accept it. At a minimum this should remove the need for any fragmentation/customization when it comes to games that directly support S3D.
With S3D out of the way, the rest of the D3D11.1 feature set isn’t going to be nearly as visible. Interoperability between graphics, video, and compute is going to be greatly improved, allowing video via Media Foundation to be sent through pixel and compute shaders, among other things. Meanwhile target independent rasterization and some new buffer commands should give developers a few more tricks to work with, while double precision (FP64) support will be coming to pixel shaders on hardware that has FP64 support.
Finally, looking at things at a lower level D3D11.1 will be released alongside DXGI 1.2 and WDDM 1.2, the full combination of which will continue Microsoft’s long-term goal of making the GPU more CPU-like. One of Microsoft’s goals has to been to push GPU manufacturers to improve the granularity of GPU preemption, both for performance and reliability purposes. Since XP things have gotten better as Vista introduced GPU Timeout Detection and Recovery (TDR) to reset hung GPUs, and a finer level of granularity has been introduced to allow multiple games/applications to share a GPU without stomping all over each other, but preemption and context switches are still expensive on a GPU compared to a CPU (there are a lot of registers to deal with) which impacts performance and reliability.
To that end preemption is being given a bit more attention, as WDDM 1.2 will be introducing some new API commands to help manage it while encouraging hardware developers to support finer grained preemption. Meanwhile to improve reliability TDR is getting a major addition by being able to do a finer grained reset of the GPU. Currently with Windows 7 a TDR triggers a complete GPU reset, but with Windows 8 and WDDM 1.2 the GPU will be compartmentalized into “engines” that can be individually reset. Only the games/applications using a reset engine will be impacted while everything else is left untouched, and while most games and applications can already gracefully handle a reset, this will further reduce the problems a reset creates by resetting fewer programs.
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SlyNine - Friday, December 23, 2011 - link
Not really, If Nvidia didn't handicap the CPU version of physx so bad than I'd be fine with it, But Nvidia purposely made the CPU version of phsyx worse totally gimped.CeriseCogburn - Thursday, March 8, 2012 - link
I agree, but that's the way it guy. The amd fans don't care what they and their reviewers pull, and frankly the reviewers would recieve death threats if they didn't comply with amd fanboy demands....So when nvidia had ambient occlusion active for several generations back in a driver add, we were suddenly screamed at that shadows in games suck.... because of course amd didn't have that feature...
That's how the whole thing is set up - amd must be the abused underdog, nvidia must be the evil mis-implementer, until of course amd gets and actual win, or even any win even with 10% IQ performance cheat solidly in place, and any other things like failed AA, poor tessellation performance, no PhysX, etc, etc, etc...
We just must hate nvidia for being better and of course it's all nvidia's fault as they are keeping the poor red radeon down....
If amd radeon has " a perfectly circular algorithm " and it does absolutely nothing and even worse in all games, it is to be praised as an advantage anyway.... and that is still happening to this very day... we ignore shimmer until now, when amd 79xx has a fix for it.... etc..
Dude, that's the way it is man....
Nvidia is the evil, and they're keeping the radeon down...
They throw around money too ( that's unfair as well - and evil ...)
See?
So just pretend anything radeon cannot do that nvidia can doesn't count and is bad, and then make certain nvidia is cut down to radeon level, IQ cheat, no PhysX, AA not turned on, Tesselation turned down, default driver hacks left in place for amd, etc....
Then be sure to cheer when some price perf calc ignoring all the above shows a higher and or lower and card to have a few cents advantage... no free game included, no eyefinity cables... etc.
Just dude... amd = good / nvidia=evil ...
Cool ?
shin0bi272 - Thursday, December 22, 2011 - link
Since I cant edit my comments I have to post this in a second comment instead.According to the released info, Nvidia’s Next Gen flagship GK-100/GK-112 chip which will feature a total f 1024 Shaders (Cuda Cores), 128 texture units (TMUs), 64 ROP’s and a 512-bit GDDR5 Memory interface. The 28nm Next Gen beast would outperform the current Dual chip Geforce GTX590 GPU.
shaboinkin - Thursday, December 22, 2011 - link
Can someone tell me why GPUs tend to have much more transistors than a CPU? I never knew why.Boushh - Thursday, December 22, 2011 - link
Basically it has to do with the difference between programs (= CPU instructions) and graphics (= pixels):A program consists of CPU intructions, many of these instructions depend on output from the previous instruction, Therefore adding more pipelines that can work on the instructions doen't realy work.
A picture consists of pixels, these can be processed in parrallel. So if you double the number of pipelines (= pixels you can work on at the same time), you double the performance.
Therefore CPU's don't have that many transistors. In fact, most transistors in a CPU are in the cache memory not in the actual CPU cores. And GPU's do.
Of course this is hust a simple explenation, the through is much much more complex ;-)
Boushh - Thursday, December 22, 2011 - link
That last line should read:'Of course this is just a simple explanation, the reality is much much more complex'
Reminds me to yet again vote for an EDIT button !!!! Maybe as a christmas present ? PLEASE !!!
shaboinkin - Thursday, December 22, 2011 - link
Interesting...Do you know of a site that goes into the finer details?
Mishera - Wednesday, December 28, 2011 - link
If you're looking for something to specifically answer you question the checking different tech sites. I think realworldtech addressed tis to a degree. Jon Stokes at arstechnica from what I heard wrote some pretty good articles on chip design as well. But if it's a question on chip architecture, reading some textbooks is your best bet. I asked a similar question in the forums before and got some great responses just check my posts.I add to what Boushh said in that for the type of information they process, it's beneficial to have more performance (and not just for graphics). That's why Amd has been pushing to integrate the gpu into the CPU. That's also to a degree show the different philosophy right now between intel and Amd in multicore computing (or the difference between Amd's new gpu architecture vs their previous one).
What it comes down to is optimizing chip design to make use of programs, vice versa. There really is now absolute when dealing with this.
MrSpadge - Thursday, December 22, 2011 - link
It's not like - as stated several times in the article - AMD is wrong about the power target of the HD7970, if they mean the PowerTune limit. Think of it as "the card is built to handle this much heat, and is guaranteed not to exceed it". That doesn't forbid drawing less power. And that's exactly what the HD6970 does: it's got the same "power target", but it uses less of its power budget than the HD7970.Like CPUs, whose real world power consumption is often much less than the TDP.
MrS
Ryan Smith - Thursday, December 22, 2011 - link
PowerTune is a hard cap on power consumption. Given a sufficient workload (i.e. FurMark or OCCT), you can make the card try to consume more power than it is allowed, at which point PowerTune kicks in. Or to put this another way, PowerTune doesn't kick in unless the card is at its limit.PowerTune kicked in for both the 6970 and 7970. In which case both cards should have be limited to 250W.