The ASUS ROG Enthusiast SLI Bridge adapter performed admirably with no issues encountered operating the system in SLI mode with the dual modded EVGA GTX 970 SC ACX 2.0 graphics cards. SLI performance in comparison to single card performance fell as expected with 50%+ performance gains across the board. The one performance caveat seemed to be the minimal impact the overclocked CPU speed seemed to have on performance. Performance gains were much more dramatic when overclocking the GPU by itself with the overclocked CPU netting < 5% performance increase in most cases.
As of June 27, the ASUS ROG Enthusiast SLI Bridge adapter was available at Amazon.com for $69.95 with free shipping.
As of June 27, the EVGA 970 GTX SC ACX 2.0 graphics adapter was available at Amazon.com for $337.99 with Prime shipping. The card was also available from Newegg.com for $314.99 after $15 mail-in rebate and B&H for $337.99 with free shipping.
Courtesy of ASUS
ASUS did a fine job in designing the ROG Enthusiast SLI Bridge from both an aesthetic and implementation perspective. The unit is solidly constructed with a brushed aluminum cover with its embedded red ROG logo, allowing it to blend in well with almost any build. Further, ASUS designed the bridge to be powered directly from the SLI connectors on supported video cards as well as externally powered via a MOLEX connector for cards that don't have direct power support. Its availability and price is questionable currently, but that will likely change in the near future with the other enthusiast-style SLI bridges starting to flood the market.
The EVGA 970 GTX SC ACX 2.0 card performance testing in SLI illustrated some rather interesting results, especially when comparing performance of the cards with stock speed and overclocked CPUs. On average, you can expect a 50% performance gain with SLI, more with GPU-based overclocking. However, CPU overclocking appeared to have little effect on the performance of the system. Most of the tests were run at 1080p because of limitations of the testing equipment available which may have led to the lackluster results with an overclocked CPU. Further, the Corsair HX750 750 watt PSU may have been a limiting factor as well, especially when pushing both the graphics cards and CPU speeds. The take-away here is that SLI does net you some nice performance gains, but you need to be mindful of your system build as well. I'd recommend no less than an 850 to 1000 watt PSU to ensure that the PSU itself does not become a bottleneck.