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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JonnyDough - Wednesday, September 23, 2009 - link
They could probably use a 1.5 GB card. :(yacoub - Wednesday, September 23, 2009 - link
why is the 5870 so freaking LONG??I'm pretty sure you could land aircraft on it.
http://images.anandtech.com/reviews/video/ATI/5870...">http://images.anandtech.com/reviews/video/ATI/5870...
Someone should photoshop a person into that image for scale. They'd be standing in the shadow underneath the PCIe connector, waving at you, and there would be an F-35 JSF circling like a fly trying to land on the deck.
Ryan Smith - Wednesday, September 23, 2009 - link
It's your standard, full-length 10.5" card. It's the same as the GTX cards and the 4870X2Here's a shot comparing it to a GTX 285 and a 4890 that I didn't get to use in the article.
http://images.anandtech.com/reviews/video/ATI/5870...">http://images.anandtech.com/reviews/video/ATI/5870...
SiliconDoc - Monday, September 28, 2009 - link
If you can't see the 5870 is the longest card in that pic, then you've got different problems than just lying issues.Another one, another big fat fib, with pic included, that proves the fib to be a fab fib.
It's amazing.
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"No, everyone, do not believe your lying eyes, it's a standard 10.5" measured in the new red rooster barnyard stick."
Cripes call International Weights and Measures, we have warped space time around the new ati card it's so powerful.
LSnK - Wednesday, September 23, 2009 - link
Or plainly spoken, angle independent angle-dependent filtering. How confusing.frozentundra123456 - Wednesday, September 23, 2009 - link
Mildly disappointed in the initial results for this card. It is powerful,admittedly, but it has less than twice the performance of the 4870. Also does not use less power. Maybe I was expecting too much. It surely is not a giant step up like the introduction of the 4xxx series cards. I was hoping for another big leap in performance per watt.I have a feeling that nVidia's 300 series will beat it when it finally comes out, although hopefully ATI will still be ahead in performance per watt and performance per dollar.
I hope they make a good low/midrange card like the 4670 that does not require external power but has increased performance.
Spoelie - Wednesday, September 23, 2009 - link
I reckon you'll see performance improve the coming months, as ATi's compiler improves to use the new instructions more efficiently. The card you see here today will not be the one fighting GT300.Granted, it won't make huge strides, but I guesstimate it to be 5-10% better, depending on circumstance/game, by the november-january timeframe (when GT300 hopefully lands).
Nvidia's baby will probably still be faster, but if the margin turns out to be slim, we'll have another rv770 vs GT200 situation playing out. And when the first wave of DX11 games have hit, somewhere next year, it'll be time to reevaluate again ;).
JonnyDough - Wednesday, September 23, 2009 - link
and I stopped. I had to post this:"Sometimes a surprise is nice. Other times it’s nice for things to go as planned for once.
Compared to the HD 4800 series launch, AMD’s launch of the HD 5800 series today is going to fall in to the latter category. There are no last-minute announcements or pricing games, or NDAs that get rolled back unexpectedly. Today’s launch is about as normal as a new GPU launch can get."
If it's normal for all that crap to happen, wouldn't it be ABNORMAL for AMD to have a great launch? :)
SiliconDoc - Wednesday, September 23, 2009 - link
LOL" . Today’s launch is about as normal as a new GPU launch can get."
I guess he meant "for reviewers" - since the "normal launch" today is "listed on the websites for sale, but greyed out, not available, or pre-order" - meaning NO STOCK.
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Yehah buddy, that is a "as normal as any launch" so long as it's the immensely favored ATI launching, and not that hated greedy Nvidia...
A normal launch and you can't buy the card...rofl.
JonnyDough - Thursday, September 24, 2009 - link
I wasn't being a fanboi, merely mocking normal launches from several companies. Seems like paper launches almost became the norm for awhile. :P