AMD's Radeon HD 5870: Bringing About the Next Generation Of GPUs
by Ryan Smith on September 23, 2009 9:00 AM EST- Posted in
- GPUs
A Quick Refresher on the RV770
As Cypress is a direct evolution of the RV770 design, before we talk about what’s new with Cypress we are going to go over a quick rehash of RV770’s internal workings. As it’s necessary to understand how RV770 was built to understand what Cypress changes, if you’re completely unfamiliar with RV770, please take a look at our expanded discussion of RV770 from last year. For the rest of you, let’s get started.
At the center of the RV770 is the Stream Processing Unit (SPU), a single arithmetic logic unit. The RV770 has 800 of these, and they are packaged together in groups of 5 and are what we call a Streaming Processor (SP). A SP contains a register file, a branch predictor, and the aforementioned 5 SPUs, with the 5th SPU being a more complex unit capable of transcendental functions along with the base functions of an ALU. The SP is the smallest unit that can do individual work; every SPU in an SP must execute the same instruction.
For every 16 SPs, AMD groups them together with texture units, L1 cache, shared memory, and controlling logic. This combined block is what AMD calls a SIMD, and RV770 has 10 of them. These 10 SIMDs form the core computational power of the RV770, and in the chip work with various specialized units such as ROPs, rasterizers, L2 cache, and tesselators to form a complete chip.
To utilize the computational power of the hardware, instruction threads are issued to the SPs. These threads are grouped into wavefronts, where there are 64 threads per wavefront. To maximize the utilization of the GPU, threads need to be organized so that they can feed all 5 SPUs in a SP an instruction every clock cycle. Doing this requires extracting instruction level parallelism (ILP) out of programs being passed to the GPU, which is difficult task of AMD’s compiler.
If SPUs go unused, then the performance of the chip suffers due to underutilization. This design gives AMD a great deal of theoretical computational power, but it is always a challenge to fully exploit it.
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shaolin95 - Wednesday, October 7, 2009 - link
So Eyefinity may use 100 monitors but if we are still gaming on the flat plant then it makes no difference to me.Come on ATI, go with the real 3D games already..been waiting since the Radeon 64 SE days for you to get on with it.... :-(
GTX 295 for this boy as it is the only way to real 3D on a 60" DLP.
Nice that they have a fast product at good prices to keep the competition going. If either company goes down we all lose so support them both! :-)
Regards
raptorrage - Tuesday, October 6, 2009 - link
wow what a joke this review is but that i mean the reviewer stance on the 5870 sounds like he is a nvidia fan just because it like what 2-3fps off of the gtx 295 doesn't actually mean it can't catch that gpu as the driver updates come out and get the gpu to actually compete against that gpu and if i remember wasn't the GTX 295 the same when it came out .. its was good but it wasn't where we all thought it should have been then BAM a few months go by and it finds the performance it was missingi don't know if this was a fail on anandtech or the testing practices but i question them as i've read many other review sites and they had a clear view where the 5870 / GTX 295 where neck N neck as i've seen them first hand so i go ahead and state them here head 2 head @ 1920x1200 but at 2560x1600 the dual gpu cards do take the top slot but that is expected but it isn't as big as a margin as i see it.
and clearly he missed the whole point YES the 5870 dose compete with the GTX 295 i just believe your testing practices do come into question here because i've seen many sites where they didn't form the opinion that you have here it seems completely dismissive like AMD has failed i just don't see that in my opinion - I'll just take this review with a gain of salt as its completely meaningless
dieselcat18 - Saturday, October 3, 2009 - link
@Silicon DocNvidia fan-boy, troll, loser....take your gforce cards and go home...we can now all see how terrible ATi is thanks you ...so I really don't understand why people are beating down their doors for the 5800 series, just like people did for the 4800 and 3800 cards. I guess Nvidia fan-boy trolls like you have only one thing left to do and that's complain and cry like the itty-bitty babies that some of you are about the competition that's beating you like a drum.....so you just wait for your 300 series cards to be released (can't wait to see how many of those are available) so you can pay the overpriced premiums that Nvidia will be charging AGAIN !...hahaha...just like all that re-badging BS they pulled with the 9800 and 200 cards...what a joke !.. Oh my, I must say you have me in a mood and the ironic thing is I do like Nvidia as much as ATi, I currently own and use both. I just can't stand fools like you who spout nothing but mindless crap while waving your team flag (my card is better than your's..WhaaWhaaWhaa)...just take yourself along with your worthless opinions and slide back under that slimly rock you came from.
dieselcat18 - Saturday, October 3, 2009 - link
@Silicon DocNvidia fan-boy, troll, loser....take your gforce cards and go home...we can now all see how terrible ATi is thanks you ...so I really don't understand why people are beating down their doors for the 5800 series, just like people did for the 4800 and 3800 cards. I guess Nvidia fan-boy trolls like you have only one thing left to do and that's complain and cry like the itty-bitty babies that some of you are about the competition that's beating you like a drum.....so you just wait for your 300 series cards to be released (can't wait to see how many of those are available) so you can pay the overpriced premiums that Nvidia will be charging AGAIN !...hahaha...just like all that re-badging BS they pulled with the 9800 and 200 cards...what a joke !.. Oh my, I must say you have me in a mood and the ironic thing is I do like Nvidia as much as ATi, I currently own and use both. I just can't stand fools like you who spout nothing but mindless crap while waving your team flag (my card is better than your's..WhaaWhaaWhaa)...just take yourself along with your worthless opinions and slide back under that slimly rock you came from.
Scali - Thursday, October 1, 2009 - link
I have the GPU Computing SDK aswell, and I ran the Ocean test on my 8800GTS320. I got 40 fps, with the card at stock, with 4xAA and 16xAF on. Fullscreen or windowed didn't matter.How can your score be only 47 fps on the GTX285? And why does the screenshot say 157 fps on a GTX280?
157 fps is more along the lines of what I'd expect than 47 fps, given the performance of my 8800GTS.
Ryan Smith - Thursday, October 1, 2009 - link
Full screen, 2560x1600 with everything cranked up. At that resolution, it can be a very rough benchmark.The screenshot you're seeing is just something we took in windowed mode with the resolution turned way down so that we could fit a full-sized screenshot of the program in to our document engine.
Scali - Friday, October 2, 2009 - link
I've just checked the sourcecode and experimented a bit with changing some constants.The CS part always uses a dimension of 512, hardcoded, so not related to the screen size.
So the CS load is constant, the larger you make the window, the less you measure the GPGPU-performance, since it will become graphics-limited.
Technically you should make the window as small as possible to get a decent GPGPU-benchmark, not as large as possible.
Scali - Friday, October 2, 2009 - link
Hum, I wonder what you're measuring though.I'd have to study the code, see if higher resolutions increase only the onscreen polycount, or also the GPGPU-part of generating it.
Scali - Thursday, October 1, 2009 - link
That's 152 fps, not 257, sorry.