Sapphire Radeon HD 5970 OC Reviewccokeman -
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There is no doubt that the Sapphire HD 5970 OC is a massive card. All of the projected measurements floating around the web were pretty much spot on, depending on where you take your measurements. The Sapphire HD 5970 OC is ATI's latest video card and features dual Cypress cores clocked a tick above the stock 725MHz clock speed at 735Mhz. The HD 5970 comes equipped with 2GB of GDDR5 memory clocked at 1010Mhz (reference is 1000MHz) runnning through a 512-bit bus that is actually 2x256-bit with 1GB dedicated to each GPU core. The card is covered in a full length shroud much like the rest of the 58XX series. The backside of the card uses a back plate that is cut out for the two cores and is used to keep the memory modules on the backside of the PCB cool as well as adding structural rigidity to the card. The top of the HD 5970 OC has vents all along the top to help vent the card. During testing I did not feel that much air was being discharged through the exhaust slots. The two GPU cores look to be packed up on the front of the card to allow for the power control circuits on the rear end of the card. You can see just how large it is by comparison to some of today's top performers. I did not have any issues fitting this card into my test case, but for those of you with mid tower cases some modification may be in order to make it fit.
The Sapphire HD 5970 OC comes with a total of three display connections, two Dual Link DVI and a single mini DisplayPort connection. The reasoning behind this is to offer as much exhaust flow through the mounting bracket as possible. With at least 300 watts of heat to dissipate, with the potential of the heatsink assembly to handle a 400 watt thermal load, the bigger the exhaust the better. This card is EyeFinity ready with this connection set. The rear view of the HD 5970 OC has the same two openings that the 5870, 5850 and 5770 have. These openings allow airflow in and over the voltage regulation circuits packed onto the back end of the card.
The Sapphire HD 5970 OC is CrossfireX capable and only has a single Crossfire bridge connection. Connecting one other 5970 gives you the power of four GPUs. The additional power consuption of the HD 5970 OC necessitated an upgrade from two 6-pin to a 6-pin plus 8-pin PCI-E power connector.
One thing ATI and its partners have been knocked around for have been the low overclocking limits that are in the Catalyst Control Center. Well, after a while the beatings around the head and shoulders start to take an effect and with this card ATI has chosen to unlock the CCC, in a manner of speaking, by upping the limits to numbers that may not be achievable without extreme cooling. ATI did not spare the hardware to make this card one that is ready for overclocking with the use of ceramic capacitors, Volterra Programmable Voltage regulators and more. The cooling solution used on the Sapphire HD 5970 OC takes a page right out of Sapphire's book and uses a vapor chamber cooling solution that can handle up to 400 watts worth of thermal load, well over the 300 watts the card is set to use based on the 75 watts through the PCI-E slot, 75 watts through the 6-pin and 150 watts through the 8-pin power connector.
If you are not sure how a Vapor Chamber heatsink works, the vapor plate is used to wick away heat, much the same way a heatpipe does. According to Sapphire's white paper on the vapor plate technology, the liquid inside the vapor plate is something we use each and every day - water, plain and simple. But water boils at 212 degrees F, right? Not when the pressure is reduced by pulling a vacuum. You can see the port where the vacuum was pulled, and the opening has been soldered shut to prevent vacuum loss. Rather than describe how the process works, I will let the blown-up images show just how simple the process really is. The last picture is a magnified image of the wicking material that is used in the assembly. From past experience, the solution has been quite effective at limiting the temperature increases on the HD 3XXX and 4XXX and 5XXX series of video cards from Sapphire. Let's see how the technology works on the 5970. I'm betting it can handle the load.
It's time to see just how well this card handles and if it is the heir apparent to the single card performance crown.