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Friday, 22 October 2010 17:38

XFX HD 6850 and Radeon HD 6870 have arrived - 6. Overclocking, Temperature, Consumption

Written by Sanjin Rados
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Review: Goes over 1GHz

AMD’s current plan is to launch 5 new graphics cards by the end of the year and it will start with today’s Radeon HD 6850 and Radeon HD 6870. Next in line is Radeon HD 6970, the fastest single-GPU card in this generation followed by the HD 6950. Cherry on top is of course the dual-GPU Radeon HD 6990.  

The graphics cards we’re talking about are AMD’s second gen DirectX 11 architecture codenamed Northern Islands. The two cards on our test today are based on Barts core, a direct result of the HD 5800 series optimization. The core is still in 40nm but the fine-tuned architecture should provide more performance per Watt and mm2 compared to the previous, Evergreen generation.

We must admit AMD picked a somewhat confusing naming scheme; namely, you’d think that Radeon HD 6870 is faster than Radeon HD 5870, which unfortunately isn’t the case. Performance wise, Radeon HD 6870 is somewhere between Radeon HD 5870 and Radeon HD 5850, whereas Radeon HD 6850 is slower than Radeon HD 5850.

Barts cards are mid-range cards that cover the $150-250 segment. Recommended pricing for the HD 6870 stands at $239 in the US and €199 including VAT. The HD 6850’s MRSP stands at $179.99 or €150 in EU. Considering the price and the promised performance, HD 6850 and HD 6870 sound like a pretty nice deal for those on the prowl for a decent gaming card.

All this means that mid range and high end graphics segments will definitely get a bit crowded – AMD will replace the HD 5800 with HD 6800 and HD 69000, so there’ll be plenty of flavors between the fastest dual-chip card and HD 5700 series.

AMD decided that the HD 5700 series will, for now, coexist with the HD 6000 series, meaning Barts, Cayman and Antilles based cards. The fastest single-GPU card from Northern Islands family will be Radeon HD 6970 and it will be based on Cayman core, whereas dual-GPU Radeon HD 6990 will have Antilles core.

HD 6890 uses Barts XT; HD 6850 uses Barts Pro core. Barts measures 255mm2, which is 31% smaller compared to HD 5870 and HD 5850’s Cypress (334mm2). Cypress has 2.15 billion transistors while our today’s GPUs come with 1.8 billion. The GPUs in question are all built in 40nm.

You can see GPU pictures of XFX HD 6870 and XFX HD 6850 cards, as well as some info AMD presented.

xfx_6870_GPUz

The Barts XT, known as the HD 6870 card, has 14 SIMDs, with 80 Stream Processor per SIMD (total of 1120 Stream Processors) and 56 texture units (TMUs). As noted it has a 256-bit GDDR5 memory interface and comes with 32 Raster Operation Processors (ROPs). The fully enabled Barts, or the Barts XT, has 2TFLOPS of computational power. The reference Barts XT GPU ended up clocked at 900MHz for the GPU and 4200MHz for 1GB of GDDR5 memory paired up with a 256-bit memory interface.

6870__specs

The Barts pro is quite similar except, of course, for the fact that it has two SIMDs less, or simply, it has 48 Texture Units (TMUs) and 960 Stream processors. This one ended up clocked at 775MHz for the GPU and 4000MHz for 1GB of GDDR5 memory paired up with a 256-bit memory interface. We've been informed that some early engineering samples with more stream processors count have been shipped, but we have confirmed that our today's test sample is the real Barts PRO deal - 960 stream processors right on the spot.

xfx_6850_GPUz

6850spec

Barts uses AMD's so called "Arch 5D" design with five stream processors; w, x, y, z and t units. Or simply there are four simple SPs and one, t unit, that handles special tasks. The SIMD remained pretty much the same compared to the Cypress GPU as you still have 80SPs per SIMD, same L1 cache size and same number of texture units per SIMD, although this time each SIMD "block" got its own Ultra-Threaded Dispatch Processor component, Instruction Cache and Constant Cache, while Cypress only had one for both blocks.

In general, Barts' SIMD consists of 16KB L1 texture, 8KB L1 compute cache and 4 texture units per SIMD. Staying on the trail of Cypress design, Barts retained the number of ROPs as well. The Barts GPU has 32 ROPs with four 128KB blocks of L2 cache memory and four 64-bit memory controllers for a total of 512KB of L2 cache and 256-bit memory interface.

AMD apparently worked hard to optimize Cypress for better performance in parallel computing as well as tessellation. Barts does have some differences compared to the Cypress, as the UVD, Display Controller and Tessellation Unit were completely redesigned. AMD's Barts GPU is also 25 percent smaller than Cypress, and impressively, only a tad slower than the Cypress based cards.

Eyefinity technology still remains one of AMD’s aces in their fight with Nvidia, and now it’s gotten even better. Namely, you now have even more outs on the card – six display controllers offer six TDMS links. Reference out configuration lists single-link DVI, dual-link DVI, HDMI and two mini-DisplayPort connectors.

Both mini-DisplayPorts 1.2 support Multi-Stream technology, which allows for using up to 3 displays on only one port, provided you use MST HUB. Of course, two DisplayPorts mean up to 6 screens. Unified Video Decoder (UVD 3.0) has also gotten an overhaul and it offers Blu-ray and DivX high definition GPU acceleration, while the card’s HDMI 1.4a connector offers support for stereoscopic 3D standards such as Blu-ray 3D.






XFX HD 6870 is a reference design card measuring 9.5 inches in lenght, just like the HD 5850. The cooling is also the reference solution – copper base and three heatpipes. The cooler looks like the one on HD 5850 cards, but the edges are sharper. Although both cards feature the same length PCB, HD 6870’s cooler is longer than HD 5850’s.

xfx6870_front

The I/O panel features two DisplayPort 1.2 connectors, HDMI 1.4a and two DVI connectors (one of them is single-link with maximum resolution of 1920x1200). By using a DisplayPort hub, it’s possible to chain up to three monitors to a single mini-DisplayPort. As far as sound goes, HDMI 1.4a provides Dolby TrueHD, DTS-HD, AC-3, DTS and up to 7.1 channel audio with 192KHz/24bit output.
xfx6870_video

Unlike the HD 5850, HD 6870 comes with only one CrossFire connector. This means that you can only use two cards in 2-way CrossFire.

Radeon HD 6870 consumes 151W at max so it will require two power connectors – 150W is the limit for one power connector.

xfx6870_power

6870-box-front

6870-box-back



6850-front

XFX’s HD 6850 is a custom design that boasts 100% Japan capacitors and comes with XFX’s in-house cooling - circular heatsink with an upsized 80mm fan. The cooling isn’t particularly quiet in idle mode but it does a good job of cooling. After all, there is RPM regulation that you can rely on to make your card quiet.

6850-front2

XFX Radeon HD 6850 features two DVIs, one HDMI and one DisplayPort.  Like its HD 6870 brother, the HD 6850 also sports a XFX-branded exhaust vent.
xfx6870_video

The entire card has a black plastic hood and large vents for hot air to escape. There is a single CrossFire connector for adding another card to your graphics setup. XFX’s HD 6850 consumes up to 127W, which makes one 6-pin PCI Express connector enough to power this card.

6850-back-1

6850-back
6850-box-front

6850-kutija-back




Testbed:

Motherboard: EVGA 4xSLI
CPU: Core i7 965 XE (Intel EIST and Vdrop enabled)
Memory: 6GB Corsair Dominator 12800 7-7-7-24
Harddisk:   OCZ Vertex 2 100 GB
Power Supply: CoolerMaster Silent Pro Gold 800W
Case: CoolerMaster HAF X
Fan Controler: Kaze Master Pro 5.25"
Operating System: Win7 64-bit
260.89_desktop_win7_winvista_64bit_english
10.10 CCC (Driver 8.782RC)




AMD introduced three quality settings within its new Catalyst AI (performance, quality and high quality) of which AMD says the following:

With the introduction of the AMD Radeon HD 6800 series and its new hardware texture capabilities, the AMD Catalyst A.I. user interface in AMD Catalyst Control Center™ has also been updated to allow direct user control over performance optimizations that may affect image quality. The new AMD Catalyst A.I. options can be found by opening the 3D settings page, selecting the “All” tab and scrolling down.

The Texture Filtering Quality slider has three settings – High Quality, Quality (default), and Performance. The High Quality setting disables all texture optimizations. The Quality setting enables a trilinear optimization as well as an anisotropic sample optimization, which are designed to have no visible impact on image quality while offering improved performance. The Performance setting enables more aggressive versions of these optimizations that offer further performance improvement, but may have a small impact on image quality.

The AMD Radeon HD 6800 series continues to support fully angle invariant anisotropic filtering, and incorporates further improvements in LOD precision relative to the ATI Radeon HD 5000 Series. These image quality benefits come with no additional performance cost and remain enabled at all Texture Filtering Quality settings.

When comparing performance and image quality against NVIDIA products, we recommend using the same Texture Filtering Quality setting in the NVIDIA Control Panel to ensure the most direct and fair comparison. However, note that as of this writing NVIDIA products do not offer a comparable anisotropic filtering option with full angle independence.

The Surface Format Optimization checkbox allows improved performance in selected games that use 16-bit floating point surfaces for HDR rendering. It is designed to have no discernable effect on image quality, and therefore we recommend it be left enabled at all times.

In our HD 6800 cards review, we used high quality settings, just like on Nvidia cards. This resulted in HD 5850 cards actually scoring higher than HD 6870. The high quality option turns off every single filtering optimization (the 5800 series is running at quality setting by default) - the point of the high quality setting is to illustrate the fact that between quality and high quality there is no difference in image quality but the performance is increased. We got the following results, but we do intend to update the review with tests at quality settings.

Updated with AMD Catalyst 10.10
xfx_vantage
Gaming tests clearly show that the previously explained testing mode (with high-quality texture filtering) affects HD 6800 performance. We will soon test whether it affects picture quality as well.


xfx_avp

xfx_dirt



xfx_metro

xfx_furmark

Tessellation tests preferred HD 6800 and it shows that AMD worked really hard to improve on this field.
xfx_tessMark

xfx_unig




HD 6800 Overclocking

HD 6870’s reference clocks are 900MHz for the GPU an 1050MHz for the memory, and our today’s XFX cards use reference design. CCC Overdrive limits the clocks to 1000MHz for the GPU and 1250MHz for the memory, so we relied on MSI’s Afterburner for our overclocking. We managed to hit 1010MHz for the GPU but only after we increased the fan RPM to 55%, where the fan ran pretty loud.

We managed to hit 990MHz for the GPU and 1100MHz for the memory by running the fan in AUTO mode, and it resulted in 8% better results in Aliens vs. Predator. Had the HD 6870 been just a tad bit louder during our tests (AUTO fan mode), we’d call the card loud, but it still isn’t unbearable.

On the other hand, the card is quiet when idle.

xfx_6870_GPUz_OC


XFX HD 6850 is also a reference clocked card – the GPU runs at 775MHz, shaders at 775MHz and the memory at 1000MHz (4000MHz effectively). The card allowed an overclock to 930MHz GPU and 1180MHz for the memory and it resulted in 18% better results in Aliens vs. Predator.

xfx_6850_GPUz_OC



Fan noise

XFX HD 6870 is pretty quiet when idle, and it doesn’t get loud during gaming either.

The XFX HD 6850, on the other hand, gets loud both when idle and when gaming and it is definitely louder than XFX HD 6870. The BIOS sets the fan to 42% RPM in idle mode making the card pretty loud. Furmark testing caused the XFX HD 6850 temperatures to go up to 65 degrees Celsius, which speaks volumes on the cooler's quality. Furthermore, it also means that you can sacrifice a couple of C and make the card quieter.

xfx_6850_GPUz_idle

XFX HD 6870 didn’t go over 84°C during our tests. The cooler was almost inaudible in idle operation (43°C), and while it gets louder in FurMark tests, it isn’t too loud. Of course, fan speed can be controlled via Catalst Overdrive.

Consumption

Faster cards usually have two 6-pin PCIe power connectors but the HD 6870 had to have two. A single Watt that is the culprit, as the card will draw 151W while one connector can supply “only” 150W. However, the additional power connector allows for overclocking beyond 900MHz.

The slower HD 6850 comes with one 6-pin power connector. As you probably already know, Barts XT and PRO chips’ die size measures 255mm2. HD 6870 consumes 19W in idle and 151W during operation whereas the 6850 draws 19W when idle and 127W during operation.

We measured our entire rig's consumption after stressing the graphics with FurMark. The tests show that HD 6870’s consumption is similar to the GTX 460 1GB.

6800_power



Conclusion

Today, AMD announced two new graphics cards – Radoen HD 6870 and Radeon HD 6850. Both these cards are based on performance oriented Barts core, for the $150-250 price segment. The HD 6870’s MSRP stands at $239, whereas Europeans will have to pay €199 incl. VAT. The HD 6850’s MRSP stands at $179.99 in the US and about €150 in EU.

We received two cards for our testing – the reference XFX HD 6870 and custom designed XFX HD 6850 which retained reference clocks. XFX made sure that you know what card is in your system by launching a custom designed HD 6850 card with in-house cooling, 100% Japanese capacitors and a unique XFX backplate.

The XFX HD 6870 is selling at €199,-, while the HD 6850 has a price tag set at €150,-.

Performance wise, both the HD 6850 and HD 6870 seem like nice deals for those on the prowl for decent graphics cards.

Nvidia cut the pricing on their GTX 460 cards yesterday, so the GTX 460 768MB holds its own versus the HD 6850, while Radeon HD 6870 is priced about €45 higher than the GTX 460 1GB and meanwhile broke under the €150,- barrier.

Radeon HD 6850 does well versus Geforce GTX 460 768MB, whereas the HD 6870 outperformed the GTX 460 1GB. Our results unfortunately can’t give an exact answer to the performance comparison between the HD 6870 and HD 5850. Namely, we tested the HD 6800 series with Catalyst AI high quality texture filtering, which wasn’t be applied to HD 5800 cards so in our update we will introduce comparable results of Radeon cards.

Both XFX cards have proven to be good overclockers and the HD 6870 allowed us to hit more than 1GHz for the GPU and 930MHz with XFX’s custom designed HD 6850. The HD 6870’s GPU reference clock is 900MHz whereas HD 6850’s ticker runs at 775MHz.

All in all, AMD’s new cards have a good price-performance ratio, nice overclocking potential, improved performance per watt ration, HDMI 1.4, DisplayPort 1.2, Eyefinity support for up to 6 screens per card, improved tessellation, etc. So, such pricing, performance and potential make it virtually impossible for us not to recommend XFX’s HD 6870 or HD 6850 cards.


(Page 6 of 7)
Last modified on Sunday, 09 January 2011 17:36
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