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PowerColor Radeon HD 5870 LCS: The GHz Limit, Broken
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1. Introduction

Back in 1923, mountaineer George Mallory was interviewed by the New York Times about his planned climb of the yet-unconquered Mount Everest. When Mallory was asked why he wanted to climb the mountain, he answered: "because it's there."

Yes, the new Radeon HD 5870 is a blazing-fast graphics card--the fastest single-GPU card in the world, in fact. So why would anyone in their right mind want to void their warranty in a wanton quest to squeeze out more megahertz from the beast? George knew the answer, and if you're reading this, we suspect you'll agree. Caution be damned, we want to know how far we can push the Cypress graphics processor.

We aren't going to settle for a small increase, either. We want to know just how far a reasonable human being can take the Radeon HD 5870, so standard air-cooling solutions aren't going to cut it. Nope, we're going to need something a little more effective. When you want to kick PC cooling up a notch, liquid cooling is the way to go. For more on the Radeon HD 5870 itself, check out our launch coverage right here.

It is only natural that we look to PowerColor's new Radeon HD 5870 LCS as the weapon of choice in our charge to slay the megahertz (or could it be gigahertz?) dragon. Equipped with a pre-installed EK water block, the card is factory overclocked and advertised to keep temperatures under 50 degrees Celsius at load. Let's start our overclocking journey by taking a closer look at the card.

2. Under The Hood And The Bundle

The Radeon HD 5870 LCS is Powercolor's top-model single-GPU Radeon card. It comes with an overclocked 875 MHz core and 1,250 MHz memory speeds, which is a moderate increase over reference speeds of 25 and 50 MHz, respectively.

The included bundle covers the basics with a CrossFire connector, a DVI-to-VGA dongle, and a quick installation card. As a bonus, the package includes a full version of Dirt 2, probably the first major game title that will come to retail with DirectX 11 features. The game requires Steam to download and install, and is scheduled to be unlocked December 4th. Our only complaint about this is that the installation card doesn't address the special issues related to the liquid-cooling block. For example, we could not determine which port was the inlet and which was the outlet just by looking at them. Also included are 1/2" and 3/8" fittings for the water block in addition to the appropriate hose clamps.

On the hardware side of things, PowerColor's LCS card appears to be a standard-model Radeon HD 5870, but with a customized EK water block attached. The design is simple but effective, and darn good looking, too.

Let's take off the block to check out what's underneath:

Notice how the block covers not only the GPU and memory, but the important-for-overclocking VRM. This is a good thing. The block is substantial and weighs just over a pound all by itself. Digging a little deeper, we'll take the cover off of the block and look inside.

The cover is composed of acetal (a thermoplastic), while the block is nickel-plated copper. Note how the small channels force the coolant to move in a wavy path, increasing the cooling surface and turbulence to theoretically maximize cooling performance.

With the water block removed, the card looks strangely paper-thin for a board we know as being so large.

The GDDR5 memory chips are difficult to read, but they are Samsung K4G10325FE-HC04 components rated for 1,250 MHz operation. Since this is exactly the speed at which the memory is clocked on the card, we're not expecting a lot of headroom for pushing it higher.

Unfortunately, the I/O bezel prevents the Powercolor HD 5870 LCS from being a true single-slot card. As you can see, that second DVI output requires a double-wide slot, even though the card's cooler can easily fit in a single-slot space. Pity.

3. Installation

Installation requires the user to attach the card to a separate liquid-cooling system. Typically, I would expect that buyers of this card will own a pre-existing liquid-cooling system for their CPU and will simply add the Radeon HD 5870 LCS to the circuit.

We're testing this video card's limits, so we will dedicate a Koolance Exos-2 system with a 750W cooling capacity exclusively to the task.

As we mentioned previously, we'd have preferred some documentation about the proper way to install the coolant hoses. Since we'd taken the block apart and examined it, we chose the ports that would force the coolant flow first to the GPU and then to the memory before being sent to the radiators for cooling.

Once the hoses are attached and the fittings are tightened, the procedure is the same as it is with any liquid-cooling system. We first ran the coolant through the card without plugging the board into our test motherboard, ensuring there were no leaks and to force any air pockets out of the block. Once we were satisfied that the air bubbles were gone, we simply plugged the card into the motherboard and secured it.

We'll be pitting PowerColor's Radeon HD 5870 against two Radeon HD 4890s in CrossFire. This should be an interesting comparison because the prices are similar (if you're comparing reference card to reference card, that is; PowerColor's water block naturally adds cost just as it would if you were to purchase water-cooled 4890s) and we expect performance to be in the same ballpark, too. However, we're counting on the Radeon HD 5870 to use far less real estate and power than two Radeon HD 4890 cards.

4. Overclocking PowerColor's Radeon HD 5870 LCS

There were many twists and turns on our PowerColor Radeon HD 5870 LCS overclocking journey. Let’s start with the fundamentals.

When it comes to Radeon graphics cards, each manufacturer imposes overclocking limits in its product's BIOS. Most overclocking tools will reference these limits to see what maximum core and memory overclock they will allow the user to set. There are some tools that can work around this limitation, but they have some drawbacks that we’ll talk about later.

The Radeon HD 5800-series has some serious overclocking potential because the GPU’s voltage can be modified on the fly, as long as you have the software tools to do this. With the right tools, overclockers can increase GPU voltage to achieve higher core clock rates, same as you'd do on a host processor plugged into your motherboard. We're looking for a maximum overclock, so this is obviously of interest to us.

There are a few tools out there for overclocking the Radeon HD 5870, the most commonly-used being ATI’s Overdrive utility built into the Catalyst Control Center. Unfortunately, Overdrive does not allow for voltage control and is limited by the BIOS-imposed restrictions, so overclockers seeking the highest performance will have to look elsewhere.

There are tools that will ignore the BIOS settings, including RivaTuner, AMD GPU Clock Tool, and ATITool. However, they have a significant disadvantage in that they don’t play nice with ATI’s PowerPlay feature, meaning that if you overclock using these tools, the card will run at full power all of the time. Using any of these to overclock, your Radeon HD 5870 will run hot and potentially draw hundreds of watts of power, even at idle. In addition, we’re not aware that any of these tools allow for substantial voltage increases. Because of these drawbacks, none of these tools provide a truly elegant solution in our eyes, so we looked for more options.

Asus offers an overclocking  tool called “SmartDoctor” that allows for flexible voltage and clock settings, thus allowing the user to push the GPU voltage up to as high as 1.5V from the stock 1.16V. The problem with this utility is that it looks at your Radeon HD 5870’s BIOS to see if the card was made by Asus. If it wasn’t, it won’t work.

Perhaps the most compelling tool of note is the MSI Afterburner utility. Co-developed by MSI and the team that’s responsible for the venerable RivaTuner utility, it offers voltage increases up to 1.35V in addition to clock speed control, and even monitors vitals such as temperatures, fan speeds, and voltages. The real beauty of this tool is that it seems to be vendor-agnostic, allowing us to run it on our PowerColor Radeon HD 5870 LCS.

BIOS Issues and Workarounds

So, all we have to do is take the MSI Afterburner utility, pump up the voltage to 1.35V, and push the card as fast as it will go, right? There is one slight problem: remember those overclocking limits coded in the BIOS that we mentioned earlier? Well, the PowerColor Radeon HD 5870 LCS in our lab has a top overclocking limit of 900 MHz core and 1,300 MHz memory. This is nothing short of pathetic for a liquid-cooled board with this card's potential. To clarify, this imposes a limit of 50 MHz over the reference core speed and 100 MHz over the reference memory speed.

We immediately contacted PowerColor and asked for a BIOS with higher overclock limits to accommodate this enthusiast card, citing other BIOS files available on the Web with much higher overclocking limits. We suggested something that would allow us to try 1,200 MHz core speeds.

PowerColor responded with a BIOS that does a bit better than the original, sporting a 1,000 MHz core and a 1,500 MHz memory limit. It might not offer the 1,200 MHz core limit we were hoping for, but it’s a step in the right direction. At the time this article was written, PowerColor told us future versions of the Radeon HD 5870 LCS will get this BIOS from the factory and customers with the original BIOS can contact the company directly for the upgraded version if they desire. Purportedly, there were about 100 boards shipped with the more limited software, so its effects should still be fairly minor.

One Card, Two Overclocks

We want to figure out how far we can go with this card, so we’re going to overclock it twice. First, we will see how the card does at PowerColor's 1,000 MHz core and 1,500 MHz memory limits.

Using the MSI Afterburner tool, we were able to push the card to 1,000 MHz core at the tool’s maximum 1.35V setting. The memory wouldn’t overclock at all without system instability and a reduction in performance, so it had to stay at the stock 1,250 MHz setting. Therefore, our first overclock was 1,000 MHz core and 1,250 MHz memory.

We originally intended to see how far the card could go, so we decided to up the ante by applying an unlocked Asus Radeon HD 5870 BIOS we came across. This Asus BIOS not only had the 1,200 MHz core limit we originally wanted from PowerColor, but it also allows us to use the SmartDoctor tool and its high 1.5V core voltage limit.

The downside to this, of course, is that flashing a non-stock BIOS will quickly void the warranty (at best) and perhaps damage the card (at worst). We’re taking the risk so you don’t have to, and you will be able to see if the danger is worth our results. Of course, we’re in no way advocating that flashing a graphics card is the smartest thing to do to a $520 add-in, and any damage you cause by trying it is obviously your own responsibility.

Using the SmartDoctor tool, we managed a maximum core speed of 1,076 MHz at 1.45V. More voltage didn’t give us any more headroom, even though our liquid-cooled temperatures were low. It looks like PowerColor’s 1,000 MHz limit might not be so bad after all. Even worse, at this high core speed, the memory caused some stuttering performance and we had to back it down to 1,219 MHz for stability, leaving us with a final core overclock of 1,076 MHz, but a memory underclock of 1,219 MHz. It is a real shame that none of these tools are able to offer us a memory voltage increase, but we did the best we could without soldering anything to the card (or frying an SMT component).

The benchmarks will show us if there is any significant advantage to using Asus' unlocked BIOS and SmartDoctor compared to the stock software that PowerColor ships (in unison with MSI's Afterburner tool).

5. Test System And Benchmarks

We're not going to waste our time benchmarking 1280x1024 or 1680x1050. If you buy this class of card, you're going to play at 1920x1200 or 2560x1600. To that end, we'll test those high resolutions with and without anti-aliasing (AA) and anisotropic filtering (AF) enabled.


Graphic Test System
CPU

Intel Core i7-920 (Nehalem), 2.67 GHz, QPI-4200, 8MB Cache
Overclocked to 3.06 GHz @ 153 MHz Bclk

Motherboard

ASRock X58 Supercomputer
Intel X58, BIOS P1.90

Networking
Onboard Realtek Gigabit LAN controller
Memory

Kingston PC3-10700
3 x 1,024MB, DDR3-1225, CL 9-9-9-22-1T

Graphics

Powercolor Radeon HD 5870 LCS
875 MHz Core, 1250 MHz Memory, 1GB GDDR5
2 x HIS Radeon HD 4890 in CrossFire
850 MHz Core, 975 MHz Memory, 1GB GDDR5

Hard Drive

Western Digital Caviar WD50 00AAJS-00YFA, 500GB, 7,200 RPM, 8MB cache, SATA 3.0Gb/s

Power

Thermaltake Toughpower 1,200W
1,200W, ATX 12V 2.2, EPS 12v 2.91

Software and Drivers
Operating System
Microsoft Windows Vista Ultimate 64-bit 6.0.6001, SP1
DirectX versionDirectX 10
Graphics Drivers

AMD Catalyst 9.10

Benchmark Configuration

3D Games

Crysis

Patch 1.2.1, DirectX 9, 64-bit executable, benchmark tool
Low Quality, Medium Textures, Shadows, Physics, Shaders, Water, and Sound, No AA

Far Cry 2

Patch 1.02, in-game benchmark
Medium Quality, No AA

World In Conflict:
Soviet Assault

Patch 1.11, DirectX 9, timedemo
Medium Details, No AA/No AF

Tom Clancy's H.A.W.X.

Patch 1.02, DirectX 10 & 10.1, in-game benchmark
Low Shadows, Sun Shafts
Medium View Distance, Environment, SSAO
High Forest, Textures
HDR, Engine Heat, and DOE On, No AA

Left 4 Dead

Version 1.0.1.5., Custom THG Benchmark
Run 1: High Settings, no AA, no AF
Run 2: High Settings, Medium Shaders, 4x AA, 8x AF

Resident Evil 5

Resident Evil 5 Benchmark Version
High Shadows and Textures, Medium Overall Detail, Motion Blur On, no AA, no AF

Fallout 3

Patch 1.4.0.6., Custom THG Benchmark
High Quality, No AA, No AF

Synthetic Benchmarks and Settings

3DMark Vantage

Version: 1.02, PhysX Off, 3DMark scores

6. Benchmark Results: 3DMark Vantage And Crysis

As always, we begin with our only synthetic benchmark, 3DMark Vantage:

The Radeon HD 4890 cards in CrossFire easily best the stock clocks of PowerColor's Radeon HD 5870 LCS, but when it's overclocked, the tables are turned. It looks like the higher core clock of the modified BIOS bests the higher memory clock of the PowerColor-supplied BIOS, but not by a huge amount.

Crysis shows us that, even with an extreme Radeon HD 5870 overclock, this title usually prefers two Radeon HD 4890s in CrossFire. In fact, our overclock does not offer much of an advantage over the stock speeds at all.

7. Benchmark Results: Far Cry 2

Far Cry 2 really shows a notable advantage to the pair of Radeon HD 4890s in CrossFire. The Radeon 5870 overclock isn’t accomplishing all that much over the stock speeds here either, and it certainly does not affect playability. But at these smooth frame rates, we still don't have room to complain.

8. Benchmark Results: World In Conflict: Soviet Assault

World in Conflict: Soviet Assault does not appear to gain much from overclocking, but it certainly shows a preference for the Radeon HD 4890 cards in CrossFire.

9. Benchmark Results: Resident Evil 5

Resident Evil 5 shows us more of the same, with the overclocked Radeon HD 5870 only able to challenge the Radeon HD 4890s in CrossFire at 1920x1200 without AA applied. Once AA is used or the resolution is increased, the 4890s win. But with high frame rates like this, there are no losers.

10. Benchmark Results: Fallout 3

Fallout 3 was obviously CPU-limited at the Ultra settings without AA and AF enabled. With 4x AA and 15x AF, only the stock Radeon HD 5870 LCS showed a slight dip in frame rates at 1920x1200, although all cards drop performance at 2560x1600. Once again, the Radeon HD 4890s in CrossFire take the win at the highest resolution.

11. Benchmark Results: Tom Clancy's H.A.W.X.

H.A.W.X. really favors the CrossFire'd 4890s, but at the highest 2560x1600 resolution with 8x AA applied, the playing field becomes level. Once again, all of the contenders offer smooth performance, although the stock Radeon HD 5870 LCS is on the verge of providing smooth performance at the highest setting.

12. Benchmark Results: Left 4 Dead

This game is so CPU-limited with these powerful graphic solutions that the results are tied across the board.

13. Power Usage And Temperature Benchmarks

The power and temperature tests are where we expect to see some real wins from the liquid-cooled Radeon HD 5870 LCS.

First, let's look at power draw, both at idle and while stressing the GPU with the 3DMark Vantage Perlin noise test at the extreme preset:

First, we will note the extremely high idle power usage of two Radeon HD 4890 cards in CrossFire. An astounding 286W is a level that many passable gaming machines won't even reach under duress. At load, the CrossFire setup is pulling almost twice that, but the overclocked 5870 card with the modified BIOS is pulling even more.

However, the stock Powercolor HD 5870 LCS and the overclocked version using the stock BIOS are pulling much more reasonable load numbers, while providing performance that almost matches the extreme overclock.

This is where the LCS will come into its own. Even pushed to the stock BIOS' overclocking limit, the card remains cooler than 50 degrees Celsius, and it takes the unlocked BIOS flash and high overclock to force load speeds above 50 degrees. Compare this to the CrossFire'd Radeon HD 4890 cards, which idle at 63 degrees Celsius and reach 80 degrees under load.

14. Conclusion

This review has given us a lot to think about and the results have surprised us quite a bit.

Radeon HD 5870 Versus 2 x Radeon HD 4890

Lets begin by considering the stock performance that the PowerColor Radeon HD 5870 LCS provides versus two Radeon HD 4890s in CrossFire. Since the PowerColor card's factory overclock was a mere 25 MHz on the core and 50 MHz for the memory, there shouldn't be a notable difference compared to the reference Radeon HD 5870 performance.

In this case, the Radeon HD 4890 CrossFire setup surprisingly achieved a handy lead over the Radeon HD 5870. This surprised us enough to give AMD a call, as we were curious why. The Radeon HD 5870 has the same number of shaders, ROPs, and texture units running at the same core clock rate as a pair of Radeon HD 4890 cards in CrossFire. The Radeon HD 5870 also sports a memory bandwidth advantage. Since CrossFire should theoretically take a scaling hit, why wasn't the single Radeon HD 5870 showing a performance win? Do the 5800-series drivers need to mature?

AMD's rep said that the explanation is likely that the Radeon HD 5870 is optimized for DirectX 11, and not DirectX 10 and 9 titles. As DirectX 11 titles are released, we'll see the 5800-series deliver even better performance.

The reasoning adds more fodder for discussion when comparing the two setups. While the Radeon HD 4890 cards delivered faster framerates, the Radeon HD 5870 also provided a smooth gaming experience at 2560x1600 with anti-aliasing applied and the highest image-quality settings selected. The only game that suffered unplayable performance on either setup was Crysis, which showed that neither solution was acceptable.

So, given the choice between the a reference Radeon HD 5870 or CrossFire'd 4890s, would you prefer smooth performance and DirectX 11 support or smoother performance and no DirectX 11? On top of that, the 4890s in CrossFire used far more power under load than the reference Radeon HD 5870. While a compelling argument can be made for either choice, this editor might choose the single Radeon HD 5870 for efficiency, simplicity, and future-proofing. However, from a pure price/performance standpoint, two Radeon HD 4890's in CrossFire can't be beat--especially considering scant Radeon HD 5870 availability.

But PowerColor's LCS card costs an extra $105 beyond the price of a reference card. More on that in a second.

Radeon HD 5870 Overclocking

PowerColor's Radeon HD 5870 LCS easily reaches the 1 GHz clock limit with a voltage increase while staying well below 50 degrees Celsius under load. Unfortunately, the memory speed wouldn't budge. Regardless, this 175 MHz increase over the reference 5870 core clock provided only a few FPS over standard speeds.

Going the extreme route and flashing an unlocked BIOS to the card only got us an additional 76 MHz on the core clock, and actually cost us some memory speed due to instability. This 251 MHz increase over the reference clock might sound impressive, but the performance increase over the stock 1 GHz limit didn't provide much performance.

Would we consider flashing our Radeon HD 5870 LCS to Asus' unlocked BIOS worth the risks? Probably not. The performance difference was so slight that we consider it an unnecessary gamble. Considering the extra power use, chance of damage, and voided warranty, keeping the stock BIOS seems to be the best option. PowerColor's 1,000 MHz core limit is acceptable in this light.

Powercolor's Radeon HD 5870 LCS

Finally, what of PowerColor's liquid-cooled beast, specifically?

First, we have to ask who this card is for. Are we suggesting that you go out and buy a liquid cooling system just to power a video card? Obviously not. The overclocked graphics performance doesn't justify this on its own, nor does it justify the ~$100 price premium for PowerColor's LCS card. The $500+ price tag of the PowerColor Radeon HD 5870 LCS brings it within about $80 of the cheapest dual-GPU Radeon HD 5970, and that's not even considering the expense of a liquid cooling system. If you're not already rocking a water-cooled setup, this should give you a lot to think about. Low temps or not, a Radeon HD 5870 with an aggressive overclock is never going to match the speed of a dual-GPU Radeon HD 5970.

No, a liquid-cooled card is attractive mostly to users who are already running a liquid cooling system for temperature and overclocking concerns. These are folks who already know the pros and cons of liquid cooling and have made their decision to go that route in spite of the extra expense. For these enthusiasts, attaching their graphics card to the existing liquid cooling circuit is likely a foregone conclusion; whether they're running a 5870, two 4890s, or a 5970, they are probably going to spend the dollars necessary to outfit the graphics subsystem for liquid cooling. 

It's really hard to comment on exact pricing right now as Radeon HD 5870 is already up $10 from its launch SRP due to low supply, but looking at Newegg most 5870s are about $410, while PowerColor's LCS is listed at $515. That's a $105 difference--about the cost of a decent full-coverage water block alone.

And this is where we see the strength of this card. For those already armed with a liquid cooling setup, PowerColor's Radeon HD 5870 LCS offers the following benefits for essentially the same price as a water block: no installation hassles or compatibility concerns, a full two-year warranty on the card that doesn't expire the moment you add it to your circuit, and a nice 1 GHz overclocking limit on the core (assuming you get the new version of the BIOS; if you don't, contacting PowerColor directly should be enough for a hook-up). For these reasons, the PowerColor Radeon HD 5870 LCS is an easy choice for liquid cooling enthusiasts looking to add a powerful GPU to their rigs. The rest of us will likely find more value elsewhere.