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
Meet the 5870
The card we’re looking at today is the Radeon HD 5870, based on the Cypress core.
Compared to the Radeon HD 4870, the 5870 has seen some changes to the board design. AMD has now moved to using a full sheath on their cards (including a backplate), very much like the ones that NVIDIA has been using since the 9800GTX. The card measures 10.5” long, an inch longer than the 4890 or the same as the 4870x2 and the NVIDIA GTX lineup.
The change in length means that AMD has moved the PCIe power connectors to the top of the card facing upwards, as there’s no longer enough room in the rear. Facing upwards is also a change from the 4870x2, which had them facing the front of the card. This, in our opinion, makes it easier to plug and unplug the PCIe power connectors, since it’s now possible to see what you’re doing.
Since the card has a TDP of 188W, AMD can still get away with using two 6-pin connectors. This is going to be good news for those of you with older power supplies that don’t feature 8-pin connectors, as previously the fastest cards without 8-pin connectors were the 4890 and GTX 285.
Briefly, the 5850 that we are not testing today will be slightly smaller than the 5870, coming in at 9.5”. It keeps the same cooler design, however the PCIe power connectors are back on the rear of the card.
With the 5800 series, DisplayPort is getting a much-needed kick in the pants. DisplayPort (full size) is standard on all 5800 series cards – prior to this it has been rather absent on reference cards. Along with a DisplayPort, the 5870 reference card contains a dedicated HDMI port, and a pair of DVI ports.
Making 4 ports fit on a card isn’t a trivial task, and AMD has taken an interesting direction in making it happen. Rather than putting every port on the same slot of the bracket as the card itself, one of the DVI ports is raised on to the other bracket. ATI could have just as easily only equipped these cards with 1 DVI port, and used an HDMI-to-DVI adapter for the second port. The advantage of going this direction is that the 5800 series can still drive two VGA monitors when using DVI-to-VGA adapters, and at the same time having an HDMI port built in means that no special adapters are necessary to get an HDMI port with audio capabilities. The only catch to this specific port layout is that the card still only has enough TMDS transmitters for two ports. So you can use 2x DVI or 1x DVI + HDMI, but not 2x DVI + HDMI. For 3 DVI-derived ports, you will need an active DisplayPort-to-DVI adapter.
With the configuration AMD is using, fitting that second DVI port also means that the exhaust vent of the 5800 series cards is not the full length of the card as is usually common, rather it’s a hair over half the length. The smaller size had us concerned about the 5870’s cooling capabilities, but as you’ll see with our temperature data, even with the smaller exhaust vent the load temperatures are no different than the 4870 or 4850, at 89C. And this is in spite of the fact that the 5870 is rated 28W more than the 4870.
With all of these changes also comes some changes to the loudness of the 5870 as compared to the 4870. The 27W idle power load means that AMD can reduce the speed of the fan some, and they say that the fan they’re using now is less noticeable (but not necessarily quieter) than what was on the 4870. In our objective testing the 5870 was no quieter than any of the 4800 series cards when it comes to idling at 46.6dB, and indeed it’s louder than any of those cards at 64dB at load. But in our subjective testing it has less of a whine. If you go by the objective data, this is a push at idle and louder at load.
Speaking of whining, we’re glad to report that the samples we received do not have the characteristic VRM whine/singing that has plagued many last-generation video cards. Most of our GTX cards and roughly half of our 4800 series cards generated this noise under certain circumstances, but the 5870 does not.
Finally, let’s talk about memory. Despite of doubling just about everything compared to RV770, Cypress and the 5800 series cards did not double their memory bandwidth. Moving from the 4870 and it’s 900MHz base memory clock, the 5870 only jumps up by 33% to 1.2Ghz, in effect increasing the ratio of GPU compute elements to memory bandwidth.
When looking back at the RV770, AMD believes that they were not bandwidth starved on the cards that used GDDR5. And since they had more bandwidth than they needed, it was not necessary to go for significantly more bandwidth for Cypress. This isn’t something we can easily test, but in our benchmarks the 5870 never doubles the performance of the 4870, in spite of being nearly twice the card. Graphics processing is embarrassingly parallel, but that doesn’t mean it perfectly scales. The different may be a product of that or a product of the lack of scaling in memory bandwidth, we can’t tell. What’s for certain however is that we don’t have any hard-capped memory bandwidth limited situations, the 5870 always outscores the 4870 by a great deal more than 33%.
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mapesdhs - Saturday, September 26, 2009 - link
MODel3 writes:
> 1.Geometry/vertex performance issues ...
> 2.Geometry/vertex shading performance issues ...
Would perhaps some of the subtests in 3DMark06 be able to test this?
(not sure about Vantage, never used that yet) Though given what Jarred
said about the bandwidth and other differences, I suppose it's possible
to observe large differences in synthetic tests which are not the real
cause of a performance disparity.
The trouble with heavy GE tests is, they often end up loading the fill
rates anyway. I've run into this problem with the SGI tests I've done
over the years:
http://www.sgidepot.co.uk/sgi.html">http://www.sgidepot.co.uk/sgi.html
The larger landscape models used in the Inventor tests are a good
example. The points models worked better in this regard for testing
GE speed (stars3/star4), but I don't know to what extent modern PC
gfx is designed to handle points modelling - probably works better
on pro cards. Actually, Inventor wasn't a good choice anyway as it's
badly CPU-bound and API-heavy (I should have used Performer, gives
results 5 to 10X faster).
Anyway, point is, synthetic tests might allow one to infer that one
aspect of the gfx pipeline is a bottleneck when infact it isn't.
Ages ago I emailed NVIDIA (Ujesh, who I used to know many moons ago,
but alas he didn't reply) asking when, if ever, they would add
performance counters and other feedback monitors to their gfx
products so that applications could tell what was going on in the
gfx pipeline. SGI did this ages years ago, which allowed systems like
IR to support impressive functions such as Dynamic Video Resizing by
being able to monitor frame by frame what was going on within the gfx
engine at each stage. Try loading any 3D model into perfly, press F1
and click on 'Gfx' in the panel (Linux systems can run Performer), eg.:
http://www.sgidepot.co.uk/misc/perfly.gif">http://www.sgidepot.co.uk/misc/perfly.gif
Given how complex modern PC gfx has become, it's always been a
mystery to me why such functions haven't been included long ago.
Indeed, for all that Crysis looks amazing, I was never that keen on
it being used as a benchmark since there was no way of knowing
whether the performance hammering it created was due to a genuinely
complex environment or just an inefficient gfx engine. There's still
no way to be sure.
If we knew what was happening inside the gfx system, we could easily
work out why performance differences for different apps/games crop
up the way they do. And I would have thought that feedback monitors
within the gfx pipe would be even more useful to those using
professional applications, just as it was for coders working on SGI
hardware in years past.
Come to think of it, how do NVIDIA/ATI even design these things
without being able to monitor what's going on? Jarred, have you ever
asked either company about this?
Ian.
JarredWalton - Saturday, September 26, 2009 - link
I haven't personally, since I'm not really the GPU reviewer here. I'd assume most of their design comes from modeling what's happening, and with knowledge of their architecture they probably have utilities that help them debug stuff and figure out where stalls and bottlenecks are occurring. Or maybe they don't? I figure we don't really have this sort of detail for CPUs either, because we have tools that know the pipeline and architecture and they can model how the software performs without any hardware feedback.MODEL3 - Thursday, October 1, 2009 - link
I checked the web for synthetic geometry tests.Sadly i only found 3dMark Vantage tests.
You can't tell much from them, but they are indicative.
Check:
http://www.pcper.com/article.php?aid=783&type=...">http://www.pcper.com/article.php?aid=783&type=...
GPU Cloth: 5870 is only 1,2X faster than 4890. (vertex/geometry shading test)
GPU Particles: 5870 is only 1,2X faster than 4890. (vertex/geometry shading test)
Perlin Noise: 5870 is 2,5X faster than 4890. (Math-heavy Pixel Shader test)
Parallax Occlusion Mapping: 5870 is 2,1X faster than 4890. (Complex Pixel Shader test)
All the above 4 tests are not bandwidth limited at all.
Just for example, if you check:
http://www.pcper.com/article.php?aid=674&type=...">http://www.pcper.com/article.php?aid=674&type=...
You will see that a 750MHz 4870 512MB is 20-23% faster than a 625MHz 4850 in all the above 4 tests, so the extra bandwidth (115,2GB/s vs 64GB/s) it doesn't help at all.
But 4850 is extremely bandwidth limited in the color fillrate test (4870 is 60% faster than 4850)
Also it shouldn't be a problem of the dual rasterizer/dual SIMDs engine efficiency since synthetic Pixel Shader tests is fine (more than 2X) while the synthetic geometry shading tests is only 1,2X.
My guess is ATI didn't improve the classic geometry set-up engine and the GS because they want to promote vertex/geometry techniques based on the DX11 tesselator from now on.
Zool - Friday, September 25, 2009 - link
In Dx11 the fixed tesselation units will do much finer geometry details for much less memmory space and on chip so i think there isnt a single problem with that. Also the compute shader need minimal memory bandwith and can utilize plenty of idle shaders. The card is designed with dx11 in mind and it isnt using the wholle pipeline after all. I wouldnt make too early conclusions.(I think the perfomance will be much better after few drivers)MODEL3 - Saturday, September 26, 2009 - link
The DX11 tesselator in order to be utilized must the game engine to take advantage of it.I am not talking about the tesselator.
I am talking about the classic Geometry unit (DX9/DX10 engines) and the Geometry Shader [GS] (DX10 engines only).
I'll check to see if i can find a tech site that has synthetic bench for Geometry related perf. and i will post again tomorrow, if i can find anything.
JarredWalton - Friday, September 25, 2009 - link
It's worth noting that when you factor in clock speeds, compared to the 5870 the 4870X2 offers 88% of the core performance and 50% more bandwidth. Some algorithms/games require more bandwidth and others need more core performance, but it's usually a combination of the two. The X2 also has CrossFire inefficiencies to deal with.More interesting perhaps is that the GTX 295 offers (by my estimates, which admittedly are off in some areas) roughly 10% more GPU shader performance, about 18.5% more fill rate, and 46% more bandwidth than the HD 5870. The fact that the HD 4870 is still competitive is a good sign that ATI is getting good use of their 5 SPs per Stream Processor design, and that they are not memory bandwidth limited -- at least not entirely.
SiliconDoc - Wednesday, September 30, 2009 - link
The 4870x2 has somewhere around "double the data paths" in and out of it's 2 cpu's. So what you have with the 5870 putting as some have characterized " 2x 770 cores melded into one " is DOUBLE THE BOTTLENECK in and out of the core.They tried to compensate with ddr5 1200/4800 - but the fact remains, they only get so much with that "NOT ENOUGH DATA PATHS/PINS in and out of that gpu core."
cactusdog - Friday, September 25, 2009 - link
Omg these cards look great. Lol Silicon Doc is so gutted and furious he is making hmself look like a dam fool again only this time he should be on suicide watch...Nvidia cards are now obsolete..LOL.mapesdhs - Friday, September 25, 2009 - link
Hehe, indeed. Have you ever seen a scifi series called, "They Came
From Somewhere Else?" S.D.'s getting so worked up, reminds me of
the scene where the guy's head explodes. :D
Hmm, that's an alternative approach I suppose in place of post
moderation. Just get someone so worked up about something they'll
have an aneurism and pop their clogs... in which case, I'll hand
it back to Jarred. *grin*
Ian.
SiliconDoc - Friday, September 25, 2009 - link
That is quite all right, you fellas make sure to read it all, I am more than happy that the truth is sinking into your gourds, you won't be able to shake it.I am very happy about it.