PowerColor HD 4850 PCS 2GB PCI-E Page: 1
Introduction & Specifications
PowerColor HD4850 2GB PCSWhen it comes to bang-per-buck (or value for money for better use of an English term) when gaming on Vista's DX10 platform, the AMD HD 4850 is widely regarded as being in a class of its own. Sure it might not able to keep up with the likes of nVidia's GTX260 in pixel pushing performance, but as our CPF (Cost Per Frame) scale has shown on many recent GPU reviews, the HD4850 is literally untouchable when seeking the best frame rates for your hard earned cash.
As many of us will already know, the ATI/AMD reference card is bundled with a 512MB GDDR3 framebuffer which is regarded by most as being pefectly adequate for a mid-range GPU. However, with some AIB partners looking to seperate themselves from the rest of the market by means of more than just a few added accessories in the box, it wasn't long before 1GB versions of the card started to appear. Of course, this in theory is fine. Double up the frame buffer, probably grab an extra few FPS at high resolutions and hopefully gain a few extra sales in the process.
But where do you stop? At what point does slapping extra memory on to a GPU go from being a marketing stunt to a total waste of good GDDR3? Today it looks like we may well be given the opportunity to answer this question as we take a look at the latest in PowerColor's "PCS" line-up - the HD 4850 2GB! Let's check out what PowerColor have to say:
2GB GDDR3 Memory with Ultra Fast Memory Bandwidth
Industry’s first 2GB frame buffer and massive memory bandwidth up to 57.6GB/sec. Memory size makes a great impact on performance, even a powerful GPU can suffer from bottlenecks due to slow and insufficient video memory.The more the memory buffer, the more the data graphics can be saved - thus eliminating the need to access system memory and providing faster graphical performance. To satisfy the latest and upcoming games requirements, PowerColor PCS HD4850 2GB can fulfill high video memory request of those games and delivers high throughput for interactive visualization of large models and high-performance for real time processing of large textures and frames, enables the highest quality and resolution full-scene anti-aliasing (FSAA).

PCS cooling system with Unique Fan Control Technology
With PowerColor PCS solution, the unique fan control technology will detect the temperature automatically, and the fan speed will adjust with it. Based on this new technology and PCS cooling system, PowerColor reduce up to 10°C temperature, provide the cool environment for gamer to enjoy the Full HD experience.
PowerColor Specs List
Going by the details available in PowerColor's press release, the PCS HD 4850 2GB looks every bit the same as their 1GB and 512MB versions. However, be it intentionally or not, there is one vital piece of information missing from the chart above which will directly affect the cards performance - memory speed.
As we can see from the screenshot of GPU-Z above, PowerColor have been forced to run the GDDR3 at 1800mhz. This is almost 200mhz shy of the default 1986mhz clock found on a reference HD 4850 card, and will undoubtedly result in a performance hit in the medium resolution benchmarks at the very least. We can only assume that this cut in memory speed is to guarantee stability with the 2GB frame buffer used on the card, which may not be able to clock as high as its 512mb counterparts.
However, let's leave the performance discussion to the benchmarks over the next few pages; and instead take a closer look at the card itself.

PowerColor HD 4850 PCS 2GB PCI-E Page: 2
Packaging & Appearance
Presented in a slimline cardboard box with dimensions not dissimilar to the graphics card contained within, the PowerColor HD4850 PCS packaging is very similar in appearance to the HD 4870 reviewed only but a few weeks ago. At the front of the box is PowerColors trademark female warrior style character (who we have to admit looks just a bit manly) along with the "PCS" logo and a couple of stickers denoting the basic specifications of the card (2GB / Dual DVI).
Powercolor 4850 Box Front  Powercolor 4850 Box Back
Around the back of the packaging are some basic bullet-point specifications along with a collection of features and short explanations. Unlike the packaging from some manufacturers, there are no hidden flaps or windows to peer into the packaging and get a glimpse of the card. This is a bit of a shame considering the rather fancy looking custom "PCS" cooling system shown further down the page.
Powercolor 4850 Box Insides PowerColor HD4850 Contents
The cards itself is protected from any courier inflicted damage by an inner-inner box, effectively placing 4 layers of cardboard between the graphics card and the outside world. Only the bare minimum accessories are included: S-Video cable, DVI-HDMI converter, DVI-VGA converter, Crossfire cable and a driver disk which is quite a disappointment considering this is essentially a premium HD4850.
PowerColor HD4850 Top PowerColor HD4850 Underneath
At first glance the PowerColor HD 4850 PCS may look just like a reference AMD card with a replacement cooler. However, when comparing the card to a few others that we had in the office it was apparent that several aspects of the cards layout have been altered. Components such as the VRM's have being moved further down the PCB and the card in general looks a bit bare. Those looking to water cool this card with a full cover waterblock should probably check for compatibility issues first.
PowerColor HD4850 Cooler PowerColor HD4850 Heatpipes
 PowerColor HD4850 Back
Finally we arrive at the cooling, and as we can see from the images above PowerColor have upgraded the stock cooling in favour of their own Zalman-like 'Flower' style cooler. Branded as the Professional Cooling System, the heat from the GPU is drawn away by a single large copper heatpipe bent into a circle. As the heat moves around the heatpipe it is dissipated by a large quantity of copper fins which are cooled by blower-style fan. The memory chips and VRM's also receive cooling via aluminium heatsinks that are securely fastened to the card with screws.

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Test Setup
Having already explored the performance of the HD4850 in several of our previous GPU reviews, today we are going to be concentrating on a head-to-head comparison of the PowerColor HD 4850 PCS 2GB vs a stock AMD HD 4850 512mb card. As mentioned previously the PowerColor is already at a disadvantage in terms of memory clock speed, but can it make up for this with a full 1.5GB of additional frame buffer? The following table shows the test system used during the benchmarking of both cards:
System Specs
The following list of games has also been chosen to test each of the cards on a number of popular game engines. Each game will be run at varying quality and AF settings at both low and high resolutions.
Quake Wars
1280x1024 / High / 4xAA
1600x1200 / High / 4xAA
1920x1200 / High / 4xAA

Unreal Tournament III
1280x1024 / DX10 / High
1600x1200 / DX10 / High
1920x1200 / DX10 / High

Call of Duty 4
1280x1024 / Max / 4xAA / 4xAF
1600x1200 / Max / 4xAA / 4xAF
1920x1200 / Max / 4xAA / 4xAF

1280x1024 / Max / 4xAA
1600x1200 / Max / 4xAA
1920x1200 / Max / 4xAA

1280x1024 / DX10 / High / 0xAA / 0xAF
1600x1200 / DX10 / High / 0xAA / 0xAF
1920x1200 / DX10 / High / 0xAA / 0xAF
1280x1024 / DX10 / High / 4xAA
1600x1200 / DX10 / High / 4xAA
1920x1200 / DX10 / High / 4xAA
Using only the the ATI Overdrive™ facility built into the driver control panel, the maximum overclock we were able to obtain from the HD4850 PCS was 680mhz on the core and 1040mhz on the memory. The Overdrive facility did actually attempt to overclock the card higher than this using the "Auto-Tune" option, but unfortunately these settings proved to be unstable when attempting to run 3DMark Vantage.
HD4850 Overclocked
The reasoning behind this poor result is more than likely due to the 2GB frame buffer. This is much like adding additional DDR memory to your system, or switching a 1GB memory module out for a 2GB one.  While you may gain the benefit of extra system memory, the margin for overclocking is often reduced. Never-the-less this is quite a poor result from the 4850, especially considering it's "PCS" cooling system.
Now let's get on to the benchmarks...

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Call of Duty 4
Call of Duty 4 is a stunning DirectX 9.0c based game that really looks awesome and has a very full feature set. With lots of advanced lighting, smoke and water effects, the game has excellent explosions along with fast gameplay. Using the in-built Call Of Duty features, a 10-minute long game play demo was recorded and replayed on each of the GPU's using the /timedemo command a total of 5 times. The highest and lowest FPS results were then removed, with an average being calculated from the remaining 3 results.
Starting off with the extremely popular CoD4, the higher stock memory clock of the reference ATI 4850 card gives it a 3-5fps advantage at all resolution settings. Unfortunately the 2GB frame buffer seems to have no positive effect for the PowerColor, even at high resolutions.
Crysis is without doubt one of the most visually stunning and hardware-challenging games to date. By using CrysisBench - a tool developed independently of Crysis - we performed a total of 5 timedemo benchmarks using a GPU-intensive pre-recorded demo. To ensure the most accurate results, the highest and lowest benchmark scores were then removed and an average calculated from the remaining three.
In all honesty we was expecting Crysis to take advantage of the larger frame buffer implimented on the PowerColor 4850, but this couldn't seem further from the case. As we can see from above, the stock ATI card manages a full 6-10fps more than the PowerColor, which in Crysis where FPS is far from plentiful, can be the difference between a slideshow and smooth gameplay.

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F.E.A.R. is a game based on the Lithtech Jupiter EX engine. It has volumetric lighting, soft shadows, parallax mapping and particle effects. All results were recorded using F.R.A.P.S, with a total of 5 identical runs through the same area of the game. The highest and lowest results were then removed, with an average being calculated from the remaining 3 results.
Once again the reference ATI 4850 takes the lead, this time by an even greater margin than Crysis over the previous page. At both 1280x1024 and 1900x1200 the higher memory clockspeed of the ATI gives it a ~10FPS advantage over the PowerColor, and at 1600x1200 this is almost doubled to a 17FPS advantage.
Racedriver GRID
Race Driver: Grid is a visually taxing game that presents a challenge to any graphics system. Results were recorded using FRAPS to log the average FPS over a 2 minute race. To ensure consistency, the same track, car and general path of travel was used in each of the 5 benchmark runs for each graphics card, with an average FPS being calculated from the median three results.
Things don't get any better for the PowerColor 4850 PCS in GRID either. With an average defecit of 5FPS against the stock ATI card across all resolutions, the results are extremely disappointing.

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Unreal Tournament III
Unreal Tournament 3 the latest game in the long running Unreal series from Epic Games and Midway. The game uses the latest UE3, which combines fast gameplay along with high quality textures and lighting effects. All benchmarks were performed using UTbench with a fly-by of the DM-BioHazard map. As usual, all benchmarks were performed 5 times, with the highest and lowest results being removed and an average calculated from the remaining three.
As expected, the story is also the same for UT3 with the PowerColor coming up around 5-10FPS short of the reference ATI card across all resolutions.
ET:Quake Wars
ET:Quake Wars is a follow-up game to Wolfenstein:Enemy Territory developed by Splash Technology. Using a modified version of id Software's Doom 3 engine along with Mega rendering technology, the game promises high resolution textures, fast gameplay and plenty of explosions. Using the built-in recordNetDemo and timeNetDemo commands, we recorded a 5 minute online gaming session and played it back a total of 5 times at each resolution, calculating the average FPS from the median three results.
Finally things seem to look up slightly for the PowerColor in ET:QW. Managing to actually beat out the reference ATI card by 1FPS (whoop!) at 1600x1200 and match it at all other resolutions, at least we've found one benchmark which isn't a complete whitewash for PowerColor.

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If we were asked to sum up the PowerColor HD 4850 PCS 2GB in a single word, our first choice would most definitely be "disappointing". PowerColor have taken a perfectly well balanced HD4850 and upset the scales by loading it with a totally unnecessary 2GB frame buffer. Not only this, but as a side-affect of this four fold increase in memory, the clock speed of the memory has had to be slashed by 200mhz in order to maintain stability in mass production.
As the results over the previous pages show, this doesn't bode well for the card as its performance is consistently lower than our reference HD 4850 across all benchmarks at both low and high resolutions. For any card to truly take advantage of a of a frame buffer this large it first needs to have the raw power and pixel pushing ability to run detailed games at resolutions higher than 1900x1200. This is something that the HD 4850 does not possess, and in all honesty even the HD4870 would probably have a hard time making full use of the 2GB.
The final nail in the coffin comes in the price. With a RRP expected to be around $250 the PowerColor HD 4850 PCS 2GB is on average $50 more expensive than a bog-standard 512MB version state-side, positioning the card extremely close to the HD 4870. Which, as we all know; offers greater performance and highly overclockable GDDR5, making it a MUCH better buy.
The Good
- Silent and effective "PCS" cooler.
The Mediocre
- Overclocking pretty poor.
The Bad
- Slower than the reference 512mb HD4850.
- Almost as expensive as a HD 4870.
Thanks to PowerColor for providing the HD4850 PCS for review. Discuss this review in our forums.
UPDATE 19/08/08
As part of our review procedure, all manufacturers are given the right to reply to any issues that arise or comments we make during the course of the review. PowerColor have chosen to excersize this right and have replied with the following statement:

This is an engineer sample in early stage of this model and we still try hard to make it performance well and then provide to customers the best product; based on the feedback produced by the Overclock3D review of our HD 4850 2GB, we have decided to make some alterations to the product before it enters the retail market. The card will now feature the same memory speed as a reference 4850 512MB giving it the same performance in games that do not make use of the 2GB frame buffer, and greater performance in games that do. The retail product will have higher clocked memory to get great performance with games.