14 DAY TRIAL // With all the attention given to TSMC's and its 28nm process that may or may not be suffering from shortages, we, like most of the world, have missed a certain other shortage issue.
There is one chip that most high-end motherboards and dual-GPU graphics adapters rely on nowadays: PCI Express 3.0 bridge chips.
Computer platforms don't support many PCI Express 3.0 lanes on their own, which means that third-party chips have to be used in order to add more.
Unfortunately, there is only one company with such bridge processors available: PLX Technology.
Even NVIDIA, the maker of the Geforce GTX 690 dual-GPU adapter, uses PLX's PEX8747, as it has none of its own.
Hardware.fr reveals that PLX Technology was surprised by very high demand and ended up selling all its initial stock to just a few companies. That left others with no choice but wait until a new batch was ready.
All in all, there is suddenly sense in the conspicuous absence of AMD's dual-GPU Radeon HD 7990, or HD 7970 X2 as OEMs call it.
The lack of PEX8747 also lies behind the general unavailability of many high-end motherboards, like ASUS' Republic of Gamers Maximus V (ASUS didn't say so, but you'd be hard-pressed to find the platform selling).
Needless to say, PC hardware makers are looking for alternatives to the PLX bridge chips, but they might not find anything similar. Worst-case scenario, they will have to make do with lower-performance products, with PCI Express 2.0 switches.
All in all, high-end motherboard and dual-GPU production and launch schedules have been disrupted, indirectly, because the PCI Express 3.0 interface turned out to be more popular than anyone had expected.
Delays will probably stop once PLX increases its production capacity or other companies begin manufacture of PCI Express 3.0 processors. We can't say for sure which will happen first and, in the end, it does not really matter all that much.