AMD's 4870 – the comeback kid

Matthew Carothers 5 Aug, 2008 at 1:00am ET Article published in Tech

The card we used for this review was an ATI-branded HD 4870 made by VisionTek and employs a reference design.

Assembled card

Teardown view

Overclocking and fan control

Thanks to the Catalyst Control Center, modest overclocking is fast and easy. For the current versions of the HD 4870, the CCC allows simple adjustments up to 790MHz on the core and 1100MHz on the memory. We’re not much for modesty so we immediately aimed high and set the sliders to their maximum. We were not disappointed. Less than five minutes after installing the drivers we were running a nice overclock which included a massive 200MHz increase to memory. This bumps the memory bandwidth up to 140.8GB/s, or just shy of the bandwidth offered by the NVIDIA GeForce GTX280. Since the CCC did not allow further increases we had to look elsewhere.

While we were able to use the AMD GPU Clock Tool to increase the speed of the card higher than 790/1100, temperature issues prevented us from maintaining them. We hope that third-party utilities will remedy this issue by permitting users to control the fan and clock speeds easily.

Hacking the fan profile

Even at stock speeds the HD 4870 was idling at a scorching 80 degrees Celsius. We thought our chances of a good overclock had been dashed by such a high temperature, but we were baffled by the full load temps being only a few degrees higher. We dug a little deeper and discovered that the fan only spun at 30% of its rated speed under both idle and load. While we appreciate the fact that this kept the card silent while idle and barely audible under load, this is clearly an overclocker’s roadblock. Or is it?

When profiles are created in the Catalyst Control Center they are stored as simple XML files that include 3D presets, clock speeds, and fan speeds. These .XML files are named after the profile they represent and are stored in the following location:

Windows XP or 2000: C:\Documents and Settings\USERNAME\Local Settings\Application Data\ATI\ACE

Windows Vista: C:\Users\USERNAME\AppData\Local\ATI\ACE\

Open the file with Notepad and scroll to the bottom of the document to look for the settings related to fan speed. Change the value for “FanSpeedAlgorith_0” to “manual” and set a static value for “FanSpeedPercentTarget_0”.

Save the file with a unique name and apply the profile in the CCC. We suggest creating a profile for all fan speeds you are interested in by editing new profiles in the same way. Once we had done this, changing fan speeds just required a right click on CCC icon in the system tray.

Throughout the course of testing, we noticed that anything higher than 38% fan speed was fairly irritating. It is also important to note that even with the fan set to run at 100% velocity we were unable to clock our card higher than 790/1100.

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Comments

5 Aug 2008 ~ 2:58pm BuddyJ Well done mas0n!
6 Aug 2008 ~ 9:02am lemonlime Great write-up, mas0n! What a fantastic card. If I were to buy a card today, this would be it!
6 Aug 2008 ~ 9:36am Zuntar Nice review Mas0n! kinda makes me want to get rid of my 8800gts 640!!
6 Aug 2008 ~ 10:11am Qeldroma I've been impressed with your developing insight into PCs, Matthew, and the freedom with which you share some of them. The Folding information was a nice touch and if you're into it, Zuntar, you may want to hang on to that GTS until they update the F@H GPU client- cause the GTS pwns it and even my HD3870 pretty much outdoes this board.

I think this series could be rescuing AMD right now from an otherwise unknown fate. It apparently scales uncommonly well in X2 and multi-GPU configurations. I'm tempted, but I'm too much into Folding to jump (hint, hint) and have been actually perusing nVidia for that reason.

Good job!
6 Aug 2008 ~ 10:59am Your-Amish-Daddy The 3800 saved them from an unknown future. The 4800 series cements it.
6 Aug 2008 ~ 8:59pm mas0n Thanks for the compliments! I think my next article may need to be on some aftermarket coolers for this beast. So far I have a Xigmatek Battle-Axe and Thermaltake DuOrb.
7 Aug 2008 ~ 1:15pm stoopid Great review. They haven't shrunk the card size I see.

Why no comparison benchmarks?
7 Aug 2008 ~ 1:29pm mas0n

stoopid wrote:

Great review. They haven't shrunk the card size I see.

Why no comparison benchmarks?

I'm glad you liked the review. I don't forsee board sizes changing significantly anytime soon. I think the market has established sizes that consumers will tolerate and the manufacturers will continue to cram as much as they can into these form factors. Also, if you look at the pictures of the VRM area on this board you can see that there is room for expansion. This makes it easier to release higher end parts in the future using the existing package.

Unfortunately I did not have any other cards available at the time of review. However, I tried to pick benchmarks that people are familiar enough with that a fairly accurate assessment could be made.