Asus Radeon HD 6870 DirectCu Page: 1

Asus Radeon HD 6870 DirectCU



So it has been a number of months since the release of the Radeon HD 6850 and 6870. While known for being strong condenders for affordable gaming applications, the product must also be able to stand the test of time. With new competition from nVidia with their GeForce GTX 560 Ti range, any enhancements over the reference 6870 is welcomed in order to remain in check. There are a handful of pre-overclocked cards available today however this time we will be taking a long hard look at the Radeon EAH6870 DirectCu.

Without wasting any further time here is an overview of today's test item.

ModelRadeon HD 6870                    
Radeon EAH 6870 DirectCu           
Stream Processors
Memory Interface



Core Frequency
Memory Frequency






Perhaps on face value it seems as though the £20 premium doesn't offer much. However if you turn over it will all begin to make sense.

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Asus Radeon HD 6870 DirectCU

A Closer Look & Initial Impressions

Those who have closely followed Asus' performance Radeon HD products will recognise the box theme of a horse driven warrior backed by a somewhat violent landscape. The design adds an aspect of 3D into the characters, which is fairly nifty; albeit not as interesting as what lies inside...

Asus Radeon HD 6870 DirectCU      Asus Radeon HD 6870 DirectCU

Don't worry we'll get to the graphics card soon, but first we have some accessories. Aside a manual, Asus persist in providing Molex to PCI-Express adapters for those who don't care for Power Supply Units. Also you will find two HDMI to DVI adapters, which many might find useful when using HDTV's perhaps.

Asus Radeon HD 6870 DirectCU      Asus Radeon HD 6870 DirectCU

...and here it is. You should have noticed by now that the key difference behind this HD 6870 is it's custom cooling solution.

Asus Radeon HD 6870 DirectCU      Asus Radeon HD 6870 DirectCU

The graphics card itself is made artifically long by nature of the fan duct design.

There are also four inputs available on the graphics card, consisting of two Displayport and two DVI-D.

Asus Radeon HD 6870 DirectCU       Asus Radeon HD 6870 DirectCU

Over the page we will discuss the differences behind the EAH6870 DirectCu in more depth.

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Asus Radeon HD 6870 DirectCU


DirectCu; simply cooler..?

 So you should have noticed that the Asus HD 6870 sports an interesting bespoke cooling design. While sometimes a manufacturer specific cooler may prove to be a cost cutting exercise, you can be assured that this is not the case for anything "DirectCu" branded. Moreover Asus claim the DirectCu unit to be as much as 20% more effective than AMD's reference counterpart. So what exactly is going on under the hood?

Asus Radeon HD 6870 DirectCU      Asus Radeon HD 6870 DirectCU

Asus Radeon HD 6870 DirectCU

As the name suggested, there are two 8mm "Direct Contact" heatpipes presented as the central focus of the main heatsink module, which stretch to either side for optimal coverage. This is all immersed in a dense array of aluminium fins for a large usable surface area. The duct is specifically designed to exhaust air in multiple directions from the centrally positioned fan, also aiding airflow coverage.

However this is where the plot thickens. The Radeon HD EAH6870 DirectCu may well be poised to perform in a quieter and cooler fashion than its stable mates, but some of the reasons behind it have nothing to do with the cooling solution. That's right folks, Asus have implemented three further physical optimisations to their graphics card to keep it chilly.


Super Alloy Choke, Capacitor & MOS...

 Asus Radeon HD 6870 DirectCU      Asus Radeon HD 6870 DirectCU

Above is the missing piece of the puzzle. Asus have incorporated alloy based electrical components to the EAH6870 PCB, which offers a mix of higher voltage tolerances, lower operating temperatures and consequently a longer operational lifespan. As with any graphics card, a lot of early stage failures are the result of weak cores or memory, a better built circuit board is beneficial for the long run.

To add a context to this, the implementation of higher quality power regulation equipment is very similar to the reasons behind choosing higher end motherboards for example. Perhaps one could consider this the choice between a Gigabyte UD3 board and a UD5.

Aside system longevity, the uprated hardware is expected to offer greater levels of tolerance for graphics card overclocking, although it is likely that you would need exotic cooling solutions to really feel the difference. We will put this to the test on the next page.

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Asus Radeon HD 6870 DirectCU


AMD Phenom II X6 1090T Black Edition
BIOSTAR TA890FXE Motherboard
4GB G-Skill Flare @ DDR3-1600
Samsung Spinpoint F1 320GB SATA II Hard Disk Drive
Asus EAH6870 DirectCu
Samsung 22x DVD+/-RW SATA
Windows 7 Home Premium x64

Temperatures & Noise

The temperatures themselves are fairly similar to the reference cooler, however what is remarkable is its considerably lower noise levels.

For a load temperature of ~79c, less than 45% fan duty speed was required. Once increased to 50% this dropped to nearer 76c. If however you have no respect for your ears (or you wear a headset) then crank the fan up to 100% for temperatures as low as 65c.

Good news all round. Finally let's get overclocking.


Asus Radeon HD 6870 DirectCU

Our overclocking endeavours were somewhat successful, as we managed to increase the 6870's operating frequencies from 915MHz / 1050MHz to 1018MHz / 1252MHz. In order to achieve this, the operating voltage had been increased to ~1.25V purely to ensure long term stability.

Despite the improved cooling performance, we deemed temperatures too high to raise GPU voltages to the levels required for a substantially higher overclock.

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Asus Radeon HD 6870 DirectCU

Unigine Heaven Benchmark

Recently Unigine produced the fantastic Heaven Benchmark. Based around a ficticious floating village the benchmark makes full use of the Direct X 11 API, most notably with the implementation of Hardware Tesselation.

Here we find the GTX 460 and HD 6870 fighting nearly neck on neck. This benchmark always seems to highlight nVidia's superior Tesselation performance.

3DMark Vantage

3DMark Vantage is Futuremarks flagship gaming oriented benchmark at present and is considered to be a demanding one at that. Our tests were carried out under the "Performance" prefix.

nVidia graphics cards hold an artificial advantage in 3DMark Vantage, due to GPU accelerated CPU tests thanks to PhysX functionality. Yet again this leaves both graphics cards with similar overall scores.

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Asus Radeon HD 6870 DirectCU


Crysis Warhead

Crysis Warhead is without a doubt one hard nut to crack, especially at higher resolutions and a dash of Anti Aliasing and Anisotropic Filtering.

This is where things get interesting. Unsurprisingly the 15MHz boost in core frequency doesn't do much for frame rates however our own overclock reaped dividends with a minimum of ~25fps and a huge lead over the cheaper GTX 460. Great success.

Far Cry 2  

Far Cry 2 is based on a rather demanding engine and also has a fair level of GPU dependancy at higher resolutions. For this test, we used the game's comprehensive benchmarking tool.

ATi's edge continues in Far Cry 2, albeit in a less spectacular fashion.

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Asus Radeon HD 6870 DirectCU

Aliens vs Predator

This game is a very recent hit that utilises many Direct X 11 features, including copious amounts of Tesselation. What a perfect way to stretch our HD 6870's legs.

Here, the HD 6870 takes a surprisingly large lead however at up to £50 more than the GTX 460, this is exactly what we were hoping to see.

Just Cause 2

Another recent hit, Just Cause 2 is also a rather demanding game; particular with all sliders maxed and the resolution set to 1920x1200. How will it run?


Again more of the same in JC2, although all of the above graphics cards were capable of producing fluid gameplay.

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Asus Radeon HD 6870 DirectCU


DiRT2 is a very recent race driving game, known for it's Direct X 11 support. Let's crank up the settings and give it a whirl...


Minor performance improvements over the sub £160 GTX 460 series but noticeable regardless. Again we see that at default speeds, the EAH6870 DirectCu is hardly quicker than the reference card.

Call of Duty - Modern Warfare 2

Modern Warfare 2 is among the most popular games available at present. With plenty of explosions and densely (polygon) populated maps, it should prove to be an interesting test for our setup.

We end on a positive note where stock for stock the EAH6870 runs circles around the GTX 460 and sees a healthy performance boost with it's overclock upwards of 1GHz.

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Asus Radeon HD 6870 DirectCU


Testing complete, what do we think?

As a product, it is without doubt a very robust item. Built from the ground up with quality in mind, you can be sure that your Asus HD 6870 DirectCu will serve you well. However there are problems.

On the whole the Asus HD 6870 performs noticeably better than the GeForce GTX 460. This in itself isn't a bad thing as the GTX 460 is a very capable graphics card, but does the performance advantage seem reasonable enough for a £30-50 higher outlay?

In plenty of ways it is; particularly in extreme cases where games such as Crysis are fully maxed out at 1920x1200 resolution. However there are also a number of applications where the performance between the two graphics cards are just a little too close for our liking. This is made worse by the launch of the GeForce GTX 560 Ti which has almost 15% more shaders than the GTX 460 and is also priced in at ~£200.

Another fundamental issue is that the Radeon HD 6870 is only priced ~£40 less than the 2GB and 1408 shader HD 6950, while the DirectCu is as little as £20 cheaper. All of a sudden it seems as though the 6870 is being priced out of its own segment by both internal and external competition.

So here's the verdict. If you're looking for a graphics card that performs similar to the high end of the previous generation (i.e.- HD 5870) then this product comes mighty close. The EAH6870 DirectCu boasts GTX 460 beating performance as well as a host of 6 series features such as 6 screen Eyefinity and 3D support. Looking for the finest Radeon HD 6870? This could well be it. Are we looking at the performance champion at £200? We don't think so. While a venerable option, the 6800 series is starting to appear a little smothered.

Excellent work Asus.

The Good
- Capable Cooling Solution
- Overclocks Well
- Robust Overclocking Software Included
- Quality Build (caps/chokes)

The Mediocre
- Pricing Very Close to HD 6950

The Bad
- None


Thanks to Asus for the sample on test today, you can discuss your thoughts in our forums.