Graphics - Published on Monday, 18 June 2012 11:45 Written by Jacob Hugosson
Currently PLX Technology is the sole actor with PCI Express 3.0 bridge chips, which has created a bottleneck on the market. This is said to be the reason for the lack of GeForce GTX 690, but also the postponed launch of HD 7970 X2 from AMD partners.
There are plenty of bridge chips for PCI Express 2.0, but for the latest 3.0 standard there is a single actor to supply all interests. PLX Technology is behind PEX8747, a so called bridge chip for connecting other circuits or units that use PCI Express 3.0 standard. Due to the high demand some companies put in large orders to have stock when the next large product cycle begins.
There is still a lack of NVIDIA GeForce GTX 690 with dual graphics circuits that uses the bridge chip in question. TechPowerUp that talked to multiple manufacturers at Computex says the lack of PEX8747 is what has hindered Radeon HD 7970X2 from launching. This has forced them to look at alternatives, like bridge chips for PCI Express 2.0. The performance difference is not that big, but it would not look good in the specification sheet.
It is also likely that this is why we haven't seen any Radeon HD 7990 with two graphics circuits, but whether this is the case or not we can only speculate.