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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Agentbolt - Wednesday, September 23, 2009 - link
Informative and well-written. My main question was "how future-proof is it?" I got the Radeon 9700 for DirectX9, the 8800GTS for DirectX10, and it looks like I may very well be picking this up for DirectX11. It's nice there's usually one card you can pick up early that'll run games for years to come at acceptable levels.kumquatsrus - Wednesday, September 23, 2009 - link
great article and great card btw. just wanted to point out that the gtx 285 also had 2x6 pins only required, i believe.Ryan Smith - Wednesday, September 23, 2009 - link
That's correct. I'm not sure how "275" ended up in there.SiliconDoc - Wednesday, September 23, 2009 - link
One wonders how the 8800GT ended up on the Temp/Heat comparison, until you READ the text, and it claims heat is "all over the place", then the very next line is "ALL the Ati's are up @~around 90C" .Yes, so temp is NOT alkl over the place, it's only VERY HIGH for ALL the ATI cards... and NVIDIA cards are not all very high...
-so it becomes CLEAR the 8800GT was included ONLY so the article could whine it was at 92C, since the 275 is @ 75C and the 260 is low the 285 is low, etc., NVidia WINS HANDS DOWN the temperature game...... buit the article just couldn't bring itself to be HONEST about that.
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What a shame. Deception, the name of the game.
Ryan Smith - Wednesday, September 23, 2009 - link
The 8800GT, as was the 3870, was included to offer a snapshot of an older value product in our comparisons. The 8800GT in particular was a very popular card, and there are still a lot of people out there using them. Including such cards provides a frame of reference for performance for people using such cards.SiliconDoc - Wednesday, September 23, 2009 - link
Gee I cannot imagine load temps for the 4980 and 4870x2 exist anywhere else on this site along with the 260,275, and 285... can you ?Oh, how about I look...
Finally - Wednesday, September 23, 2009 - link
Nvidida-Trolls tend to turn green when feeling inferior.SiliconDoc - Wednesday, September 23, 2009 - link
Turning green was something the 40nm 5870 was supposed to do wasn't it ?Instead it turned into another 3D HEAT MONSTER, like all the ati cards.
Take a look at the power charts, then look at that "wonderful tiny ATI die size that makes em so much money!" (as they lose a billion plus a year), and then calculate that power into that tiny core, NOT minusing failure for framerates hence "less data", since of course ati cards are "faster" right ?
So you've got more power in a smaller footprint core...
HENCE THE 90 DEGREE CELCIUS RUNNING RATES, AND BEYOND.
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Yeah, so sorry that it's easier for you to call names than think.
RubberJohnny - Wednesday, September 23, 2009 - link
LOL...replying to your own post 3 times...gettin all worked up about temps...PUTTIN STUFF IN CAPS...Looks like this fan boy just can't accept that the 5890 is a great card. Not surprising really, these reviews always seem to bring the fanboys/trolls/whackos out of the woodwork.
Once again, good job AT!!!
JarredWalton - Thursday, September 24, 2009 - link
SiliconDoc, you should try thinking instead of trolling. Why would the maximum be around 90C? Because that's what the cards are designed to target under load. If they get hotter, the fan speeds would ramp up a bit more. There's no need to run fans at high rates to cool down hardware if the hardware functions properly.Reviewing based on max temperatures is a stupid idea when other factors come into play, which is why one page has power draws, temperatures, and noise levels. The GTX 295 has the same temperature not because it's "as hot" but because the fan kicked up to a faster speed to keep that level of heat.
The only thing you can really conclude is that slower GPUs generate less heat and thus don't need to increase fan speeds. The 275 gets hotter than the 285 as well by 10C, but since the 285 is 11.3 dB louder I wouldn't call it better by any stretch. It's just "different".