What all that extra power gets you

Just a couple of weeks back AMD released the new Radeon HD 6990 4GB graphics card to world and it was easily crowned the king of the GPU world. With performance that beat out AMD’s own Radeon HD 5970 and walked past the single GPU based GeForce GTX 580 1.5GB from NVIDIA, the HD 6990 offered the most performance in the smallest space you could buy – and for a hefty $699 MSRP.

Just a couple of weeks back AMD released the new Radeon HD 6990 4GB graphics card to world and it was easily crowned the king of the GPU world. With performance that beat out AMD’s own Radeon HD 5970 and walked past the single GPU based GeForce GTX 580 1.5GB from NVIDIA, the HD 6990 offered the most performance in the smallest space you could buy – and for a hefty $699 MSRP.The Leftovers

Just a couple of weeks back AMD released the new Radeon HD 6990 4GB graphics card to world and it was easily crowned the king of the GPU world.  With performance that beat out AMD’s own Radeon HD 5970 and walked past the single GPU based GeForce GTX 580 1.5GB from NVIDIA, the HD 6990 offered the most performance in the smallest space you could buy – and for a hefty $699 MSRP.  (Note that they are selling for more than that as of today…)

One of the interesting features of the card was a unique hardware switch on the top of the card that is used to switch between standard clock rates of 830 MHz and a 375 watt power rating and a higher voltage, higher clock rate along with the ability to breach the 375 watt limit set by the PCI Express standard. 

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Along with the move from 830 MHz core clock to a 880 MHz core clock (which by itself wouldn’t really be notable), the HD 6990 cards move from a voltage of 1.175v stock to a slightly improved 1.2v for additional overclocking headroom.  In conjunction with this, the PowerTune implementation (which uses hardware to limit maximum power consumption levels) gets tweaked to allow for more power consumption.  This is good news for overclockers again.

Here is my quote from the original HD 6990 story:

When you move that BIOS switch on the HD 6990 from the standard setting to the overclocked setting, you aren’t just changing the clock speed of the GPU but you are also changing the default settings for PowerTune.  Instead of a target load power consumption of about 375 watts, the overclocked card will be able to target as high as 450 watts using some updated and improved circuitry on the board.  It is worth nothing though that AMD is forced to make this 450 watt option an "overclocked" setting because it does exceeded the power draw of the PCI Express slot and associated connectors and would cause a fit for vendors attempt to selling systems using the HD 6990 to consumers.  Enthusiasts that buy this card themselves though will have that option and we are glad that AMD continues to support readers like ours by enabling this type of thing.


Unfortunately, because of some time constraints, we didn’t get to play around with this overclocked setting originally but today, we rectify that situation. 

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In our story today you will see a collection of benchmarks, all run at the 2560×1600 resolution that actually stresses the HD 6990, comparing the default 830/1200 speeds to the automatically overclocked settings of 880/1250 that result from flipping that overclocking switch.  Though I realize that not many users have 30-in displays with 2560×1600 screens, the higher pixel count should also represent performance scaling and changes on multi-display Eyefinity configurations. 

After those tests, you will see our experiences with additional overclocking attempts through AMD’s Overdrive software in the Catalyst Control Center.

Our testing configuration was the same as all of our recent GPU articles:

  • Testing Configuration
  • ASUS P6X58D Premium Motherboard
  • Intel Core i7-965 @ 3.33 GHz Processor
  • 3 x 2GB Corsair DDR3-1333 MHz Memory
  • Western Digital VelociRaptor 600GB HDD
  • Corsair Professional Series 1200w PSU
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