Sapphire's HD 7950 Flex is a solid implementation of a custom design, overclocked HD 7950. It comes with a unique feature, which is support for three HDMI/DVI monitors without the need for an active DisplayPort to DVI adapter. AMD has engineered their Tahiti GPU in a way that limits it to generating two TMDS clock signals for HDMI/DVI monitors. Sapphire added a small extra display controller chip which provides a third clock signal, adding support for the third monitor.
In terms of raw performance we see about 6% improvement compared to the AMD reference board, which is a nice speed boost. Unfortunately memory is not overclocked, which would be easy to do, as the card reached an amazing 1865 MHz memory clock after we manually increased memory speeds. Overclocking in general works well, even though the maximum GPU clock is about 50 MHz lower than on some other HD 7950 cards we tested before. Overall manual overclocking yields an impressive 22% real life performance improvement, which puts the card between GTX 670 and GTX 680 in performance.
Sapphire's five heatpipe, dual fan cooler reduces idle fan noise massively. Basically the card will be inaudible during non-gaming tasks. Once you start loading the card with gaming, the fan will make its presence felt, ending up much quieter than the AMD HD 7950 reference board, but not as quiet as other custom HD 7950 cards we tested.
Surprisingly power consumption is significantly higher than the AMD reference design, for which I have no explanation. The board design is similar and voltages are same or lower, too. While the increase in power consumption is not a dealbreaker, it is still higher than expected.
With a retail price of $380, $20 higher than the cheapest HD 7950, the card is reasonably priced considering you have to pay $30 for an active DP to DVI adapter for triple monitor EyeFinity. The included HDMI cable offsets the cost a bit, too, but these cables can be found really cheap nowadays. HD 7950's biggest competitor right now is NVIDIA's GTX 670, which supports three monitors natively without any special adapters and offers higher performance with better performance per Dollar overall.