![[H]ardOCP](/images/blank.gif){kind=small}
- Date:
- Thursday , November 15, 2007
- Author:
- Brent Justice
- Editor:
- Kyle Bennett
- Google +1
ATI Radeon HD 3800 Series
The ATI Radeon HD 3800 series graphics cards are here. We will explore performance in Crysis, Unreal Tournament 3, NFS: Pro Street, and TimeShift. We can now recommend two ATI graphics cards for your gaming needs.
Introduction
It has been four months since AMD’s last ATI Radeon Graphics product launch, that being the ATI Radeon HD 2600 XT in July. The Radeon HD 2600 XT was a lower-end mainstream GPU positioned around the $149 price range. The Radeon HD 2600 XT had scaled down specifications compared to the Radeon HD 2900 series architecture, with 120 stream processors, 4 ROPs and 8 Texture Units. In our testing we found the Radeon HD 2600 XT was not able to compete in gaming as it performed rather poorly. This left a very large gap between it and the $399 Radeon HD 2900 XT. ATI needs to fill the gap between the Radeon HD 2600 XT and Radeon HD 2900 XT, and today they are releasing a product that will do exactly that.
New Series and Product Lineup
The ATI Radeon HD 3870 and ATI Radeon HD 3850 are the two new video cards being launched today. Note that the naming scheme has changed with this new series, gone are “Pro” and “XT” indicators. Using the 3870 as an example, the “3” indicates the generation, the “8” indicates the family and the “70” indicates the variant. So to make a comparison “xx50” would be the equivalent of a “Pro” and “xx70” would be the equivalent of an “XT.”
At the high-end enthusiast level, AMD is still banking on a dual-video card solution to cater to that market. This will be accomplished via two Radeon HD 3870 cards in CrossFire. A single Radeon HD 3870 will be priced at $219 MSRP and the new Radeon HD 3850 is positioned in the mainstream at $179
Architecture
Take everything you know about the Radeon HD 2900 XT’s architecture and apply it here, with a few additions. The layout is the same with both the Radeon HD 3850 and 3870 containing the full 320 stream processors, 16 Texture Units and 16 ROPs just like the Radeon HD 2900 XT. It is unfortunate that the ROPs and Texture Units have not been bumped up on the high-end product, but at least none have been scaled down, even on the 3850. This means the same shader processing capabilities can be found on the 3850 and 3870 compared to the Radeon HD 2900 XT, with only clock speed differences affecting shader performance.
The memory bus however, has been cut down compared to the Radeon HD 2900 XT. The Radeon HD 2900 XT uses a 512-bit external memory bus and a 1024-bit internal memory ring bus. The Radeon HD 3850 and 3870 have been cut down to an external 256-bit memory bus and internal 512-bit ring bus which also cuts board costs. However, GDDR4 memory modules are in use on the 3870 so that they can be clocked at high frequencies to allow high memory bandwidth.
What has been added, that the Radeon HD 2900 XT did not have, is DirectX 10.1 support. DirectX 10.1 will be introduced in Windows Vista service pack 1 sometime in the first half of 2008. There are some new requirements that DX 10.1 will enforce to be able to call a GPU DX10.1 capable, but most of these features are already present in DX 10 video cards. These specifications are mainly to keep hardware GPUs on a level playing field, for example a DX 10.1 GPU must support at least 4X multisampling antialiasing, and both ATI and NVIDIA GPUs have supported this for a good while. We will talk more about DX 10.1 and what it means to you and me in the conclusion.
CrossFireX
Quad-GPU support from ATI is finally a reality with ATI CrossFireX technology. This new technology allows multiple GPU scaling with overclocking and new display modes. Quad-GPU support will be allowed on AMD’s 790FX chipset, and as you can see in the picture is accomplished using the CrossFire bridge connectors in the configuration you see above. This means there will also be support for a triple-GPU configuration as well.
We are finally excited to see improvements in multi-display support with multi-GPUs. It has been a very annoying issue that with CrossFire (and SLI) you cannot use multiple displays; you must disable CrossFire (or SLI) to use multiple displays in 2D. With a new driver coming in January 2008 and RD790 you will be able to use up to 8 displays (with four video cards) with CrossFire. AMD has a video up on You Tube of Flight Simulator X running across 8 displays with CrossFire, which is very impressive to say the least.
PCI Gen 2 and UVD
Also new is PCI-Express 2.0 support.. This may not have any benefits right now in a single-GPU configuration, but with dual, triple or quad-GPUs this could potentially be advantageous to performance.
The UVD engine is also now supported in both the Radeon HD 3850 and Radeon HD 3870, which was not present in the Radeon HD 2900 XT. The UVD engine allows full hardware acceleration for HD-DVD and Blu-Ray, but note that it still up-scales at 2560x1600. Hardware HDCP and HDMI are also supported on both video cards.
Lower Power Finally via 55nm
The Radeon HD 3850 and Radeon HD 3870 are the first GPUs to be manufactured on TSMC’s 55nm processes. This is quite exciting as it helps reduce power and cost. The Radeon HD 2900 XT was using an 80nm processes, which as you all know ate up a lot of power with those 700 million transistors. The Radeon HD 3800 series contains 666 million transistors at 55nm. The power savings are huge compared to the Radeon HD 2900 XT. The official specifications are a peak power draw of 95 Watts on the Radeon HD 3850 and 105 Watts on the Radeon HD 3870, compare this to 215 Watts on the Radeon HD 2900 XT. The Radeon HD 3870 draws over 100 Watts less power and is even clocked at a higher frequency than the Radeon HD 2900 XT.
To aid even more in power savings both video cards utilize ATI’s PowerPlay. With PowerPlay there is automatic control of engine and memory clocks and voltages depending on GPU activity. This also allows full 3D clock speeds in windowed games; previously you would not receive full 3D clock speeds in windowed mode with the Radeon HD 2900 XT.
Specs
Here are the full specs compared:
As you can see both the Radeon HD 3850 and Radeon HD 3870 have 320 stream processors, 16 ROPs and 16 Texture units. The Radeon HD 3870 is clocked faster than a Radeon HD 2900 XT; 777 MHz, versus 740 MHz for the Radeon HD 2900 XT. This isn’t a big clock speed advantage, but it is slightly noticeable in games since, with this architecture, when you overclock the core you are also overclocking the stream processors. The Radeon HD 3850 is clocked at 670 MHz, so the only difference in shader performance between the 3850, 3870 and 2900 XT is clock speed.
On the memory side of things both video cards operate on a 256-bit external memory bus, while the 2900 XT uses a 512-bit external memory bus. The Radeon HD 3870 uses 512 MB of GDDR4 clocked at 2.25 GHz, giving us a memory bandwidth of 72 GB/sec (106 GB/sec on the 2900 XT.) The Radeon HD 3850 uses 256 MB of GDDR3 at 1.66 GHz for 53.1 GB/sec of memory bandwidth. It will be interesting to see if people can get their 3850 cards up to 3870 clock speeds with overclocking. We will do a bit of testing ourselves later in this evaluation.
Today’s Testing
The Radeon HD 3850 is priced at $179, this compares directly with a factory overclocked GeForce 8600 GTS. We are going to use an EVGA GeForce 8600 GTS Superclock (720 MHz/2.1 GHz) which on Newegg was $179 at the time of writing this. This is a highly overclocked video card and will represent the 8600 GTS GPU in the best light possible.
For the Radeon HD 3870 things are slightly more complicated. The MSRP on the Radeon HD 3870 is $219, and we are assured at launch it will be at this price with some retailers. Obviously pricing will vary a bit, but we should not see a situation like with the 8800 GT currently selling way above suggested retail pricing. The GeForce 8800 GT was positioned to be between $199-$249, but so far we have not seen it that low (except for a very few cards that sold out quickly). Stock clock 8800 GT cards are even selling for $299 at some retailers. The lowest price at Newegg at the time of writing this for an 8800 GT was $269, and those were out of stock. In fact every 8800 GT at Newegg was out of stock at the time of writing this and the average price was $293. As it stands right now, going by street price, the Radeon HD 3870 is much less expensive, and not price comparable with an 8800 GT.
While we know some people will complain about our comparisons, the fact of the matter is that currently there is a huge gap in between comparable products and it looks as if that is the area that AMD is targeting.