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Heat And Noise

ATI Radeon HD 5870: DirectX 11, Eyefinity, And Serious Speed
By , Fedy Abi-Chahla

When you start talking about cutting edge graphics, you have to address heat and noise—the collateral damage of complex GPUs and high clock rates under the duress of synthetic 3D loads.

Heated air vents out the back and top of the card.Heated air vents out the back and top of the card.

We’ll actually begin by touching on Nvidia’s GeForce GTX 285, though. With one of these cards in a gaming machine, you’re probably in peachy shape. Toss a couple into an X58-based board like our Asus Rampage II Extreme (with its slots spaced just wide enough for dual-slot graphics cards) and you’re asking for trouble, though. We had to manually key in 100% duty cycles for both boards to keep them from crashing in games like S.T.A.L.K.E.R., since the fan couldn’t spin up fast enough. At full tilt we achieved stability, but at the expense of more than 54 decibels of noise.

It's not like the GeForce GTX 295 treated us much better. In fact, once we hit 99 degrees in FurMark, we stopped our acoustic testing for fear of frying the card (it was already pumping a special smell into the room). That board’s fan was generating 54.6 decibels up until we shut it down.

But a pair of Radeon HD 5870s was the loudest combination in our tests, generating 54.7 decibels from our plucky little Extech 407768. These cards actually did hit 100 degrees C, at which point they’d throttle, dip back to 99, and then hop back up to 100. What you really need to be careful with in a closed case, though, is a rising ambient. The Radeon HD 5870’s decked-out bracket doesn’t have a full slot’s worth of ventilation anymore, so half of the card’s air actually blows out the top back into your chassis.

Overclockers—especially those with the dosh to purchase more than one Radeon HD 5870—need to make sure they’re handling cooling, since the 5870 behaves a little differently than any of ATI’s other high-end boards (more like a GeForce GTX 295, which also exhausts super-hot air into your case).

At idle, a single Radeon HD 5870 is just slightly louder than its predecessor—on par with a pair of GeForce GTX 285s in SLI, but quieter than a single GeForce GTX 295. Most impressive is the Radeon HD 4870 1GB, which is noticeably less noisy than any of the other cards, despite the fact that it’s only .6 dBA away from the GTX 285.

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