We’ve known for some time that R600 was going to require a new 8-pin PCI-Express power connector that is a part of the PCI-Express 2.0 standard. The new connector is capable of delivering up to 150W of additional power to the card – this is double what the ‘old’ 6-pin connector delivers.
While this is true, the card only requires the additional power that is provided by the 8-pin connector if you’re overclocking the card. For some of our initial testing, we used an OCZ GameXStream 700W power supply (which only comes with a pair of 6-pin power connectors) before moving to an Enermax Galaxy 1000W DXX PSU for our CrossFire testing as it comes with a pair of 8-pin connectors.
We didn't encounter any problems with stability while using two 6-pin PCI-Express power connectors – the only difference we encountered was that the Overdrive menu option wasn’t visible in Catalyst Control Center, meaning that there was no overclocking available. Of course, you can try your luck with third party overclocking tools, but ATI obviously doesn’t recommend overclocking without the 8-pin connector – it wouldn’t remove the Overdrive menu option if it was recommended.
In comparison to the HD 2900 XT, Nvidia’s GeForce 8800 GTX and Ultra both require a pair of 6-pin connectors or up to 150W of additional power and this doesn’t change when you’re overclocking. The GeForce 8800 GTS – the card that AMD has targeted on price with the HD 2900 XT – only requires one 6-pin PCI-Express power adapter whether you’re running at or above the card’s standard clock speeds.
Back when ATI introduced the Radeon X1950 Pro and its RV570 graphics processing unit, the company finally released a CrossFire solution that didn’t require a lot of unnecessary messing around. There was no longer a need for two different cards – you could just buy two of the same and they’d work together in tandem. The dreaded external CrossFire cable was gone, too.
However, ATI’s high-end products based on R580 still used the old and rather messy CrossFire implementation. Thankfully, that solution can now be left in the past, as R600 implements native CrossFire support. This is a massive improvement, as it makes installing and setting up a CrossFire system as easy as it possibly can be.
Hopefully we’ll see partners shipping standard Radeon HD 2900 XTs with one CrossFire connector in each box. Unfortunately we have to say this in hope, because there was at least one partner that shipped a standard Radeon X1950 Pro and a Radeon X1950 Pro CrossFire Edition (with two CrossFire connectors in the box)!
ATI's CrossFire connector