HiTechLegion and Hardware Canucks have posted a review on the Sapphire Radeon HD5870 and HD5750 Vapor-X Edition. Here's a bit:

We can't really conclude this review without talking about HD 5870 cards in general and how they are currently placed in the market. There shouldn't be a shadow of a doubt that they are able to reign supreme among single GPU cards but things become of bit murkier performance-wise when compared to dual GPU cards like the GTX 295 and HD 4870 X2. Considering the HD 5870's specifications, it should put up a great fight –and it does- but due to bandwidth restrictions posed upon it, the dual GPU cards are able to pull into the lead. That being said, the fact that ATI has a card that can compete with the last generation's best while being much more efficient speaks volumes of the strides they have taken. Unfortunately, limited initial availability and the substantial price gap between it and the HD 5850 have somewhat tempered peoples' enthusiasm.

One way or another, the HD 5870 remains an extremely popular card and it is great to finally see Sapphire release a card we have been seeing leaked images of for weeks now. Their HD 5870 Vapor-X is really a jack of all trades that excels in every meaningful area and then some. To say that we were satisfied by its performance is an understatement of epic proportions since it was able to consistently beat a stock clocked card while offering some truly awe-inspiring cooling performance.

Speaking of cooling performance, we should mention straight off the bat that the efficient 40nm core on the HD 5870 allows even the reference heatsink to put down some very respectable numbers. However, Sapphire has leveraged their Vapor-X technology to move thermal performance from merely good into the realm of incredible. What makes matters even better is the fact that as a whole, the design of this particular Vapor-X heatsink looks absolutely stunning. The one unfortunate thing about Sapphire's advanced heatsink is the fact that most of the hot air stays within your case and very little is exhausted out the back. If you have a modern enclosure with good airflow, this will prove to be a non-issue but in cramped cases with a single 120mm (or smaller fan) pushing out air, things could get a bit hot. In addition, from a subjective perspective, there really isn't a significant acoustical difference between the Vapor-X heatsink's fan and the one found on the stock cooler. They are both quiet as mice.