iBUYPOWER Erebus GT Review: Ivy Bridge and NVIDIA's GeForce GTX 680 in SLI

Re-Introducing the iBUYPOWER Erebus GT

It was only a month-and-a-half ago that we were able to test the iBUYPOWER Erebus GT, a boutique desktop with a custom water-cooling loop at a very compelling price for what you got. Yet in the intervening period the computing landscape has actually changed fairly drastically, with NVIDIA's GeForce GTX 680 coming to market and Intel releasing the Ivy Bridge-based Core i7-3000 series processors. Our previous review unit focused more on value proposition with a single AMD Radeon HD 7970 handling graphics duties, but the one we have on hand today is a true war machine.

We've covered Ivy Bridge extensively up to its launch and exhaustively this week, with a breakdown of the architecture and performance, analysis of its overclocking potential, testing in an HTPC environment, benching the notebook version, and even a vendor discussion and Q&A with ASUS of the Z77 platform that accompanies it. Today we have a firsthand look at how Ivy Bridge is going to handle and overclock in the field courtesy of an updated Erebus GT from iBUYPOWER, along with our first taste of a pair of NVIDIA GeForce GTX 680 graphics cards in SLI running on the platform.

There's no question that Intel's made a major achievement with Ivy Bridge: IPC is up, power consumption and die size are down, so that's pretty much win-win for all involved. Yet there's one discipline Sandy Bridge has excelled in that Ivy Bridge has a bit harder of a time with: overclocking.

The Erebus GT system that was equipped with Sandy Bridge was able to hit a 4.6GHz overclock on the Core i7-2700K, while the refreshed system with a Core i7-3770K is only able to go up to 4.4GHz, and we expect this is going to be about as high as Ivy Bridge is going to consistently go. So the question becomes: are the IPC improvements in Ivy Bridge enough to make up for the reduced overclocking headroom? We'll find out in a moment, but first here's the rundown of the updated Erebus GT.

Compared to the last unit we reviewed, we're looking at what theoretically could be a wash in terms of CPU performance (4.6GHz i7-2700K vs. 4.4GHz i7-3770K), but pretty dramatic improvements most everywhere else. The ASUS Sabertooth Z77 leverages the i7-3770K's PCIe 3.0 support along with USB 3.0 connectivity, and it includes Intel's highly desirable gigabit ethernet NIC as opposed to the Realtek controller more commonly found.

The other elephant in the room, or elephants, are the pair of NVIDIA GeForce GTX 680 cards in SLI. NVIDIA got rid of the hot shader clock in Kepler, but in the move to 28nm they also basically tripled the number of CUDA cores from GF100/110. Do some vulgar math and that works out to about 50% more shader power per GPU than the GTX 580, and you get to enjoy NVIDIA's generally excellent SLI support. That said, as has been mentioned before, the GTX 680's memory bandwidth nears 200GB/sec but still doesn't scratch the ~250GB/sec the AMD Radeon HD 7970 offers, and the GTX 680 is also working with a smaller framebuffer with 2GB of GDDR5 instead of the 7970's 3GB. Still, the 680 has been fast enough to be crowned the fastest single-GPU video card available, so theoretically two of them should be screaming fast.

Finally, we have a hefty 1200W, 80 Plus Gold power supply from Corsair, an Intel SSD, and 16GB of Corsair Vengeance DDR3 running at 1600MHz. There's very little to complain about here, the parts employed are top shelf from start to finish.