Getting Educated on the Status of PCI-E 3.0
By Rajiv Kothari on December 12, 2011
Recently, motherboard manufacturers have been fighting their hardest to differentiate their products from one another in an effort to re-invigorate the stagnant PC business. A lot of this messaging has taken a very aggressive turn, where companies have blatantly called out or attacked competing products for not being the real deal or being up-to-speed.
The harsh reality is that motherboards are generally going to stay within a certain performance range. It boils down to add-in value like UEFI BIOS, native USB 3.0 support, premium sound cards or higher-end network adapters to really gain a competitive advantage.
So it is no surprise that when PCI-E Gen 3 was announced, it caught the eye of enthusiasts who have an insatiable demand for speed. At eight Giga Transfers per second (8 GT/s) bit rate, the bandwidth was doubled for PCI-E 3.0, making it the natural evolution from the long-in-the-tooth 2.0 standard. It also became a race for marketing departments to see who could implement this technology first as a way to grab this high-end, influential market.
“Future-Proofing” is a word that gives the notion of an extended life cycle for a product, but it should be taken figuratively. There is no possible way to actually future-proof technology, considering that the whole purpose of it is to constantly evolve into something better and faster. However, it strikes a chord with customers when you can let them know they won’t have the feeling of “buyer’s remorse” within a short period of time.
Everyone wants their PC to last a very long time. As hardware enthusiasts, we know the reality is that your average PC has a lifespan of three to four years at most. But ask any mainstream buyer how long they’d like to keep their current system and they are looking at closer to six or seven years. It is with this mentality that the messaging behind PCI-E 3 hoped to resonate with consumers. What is important to know are the methods being used to market the current generation of motherboards as “PCI-E 3 Ready” and if you are getting the real deal.
The changes in architecture for Sandy Bridge made it so that PCI Express lanes are all handled by the processor. The PCI-E lanes coming out of the CPU get split, running eight lanes to the first PCI-E slot and then another eight lanes into the switch chip. The switch then looks at your configuration to control bandwidth to a single x16 slot (routing the lanes back to pair up with the eight coming from the CPU) or as dual x8 slots (routing the lanes to the second slot).
Naturally, this means that newer Gen 3 speeds also would have to come from these lanes, but unfortunately, support for the Gen 3 won’t officially happen until Intel’s Ivy Bridge processors hit the market in early 2012. The circuitries inside the current Intel 6-series chipset motherboards are theoretically capable of a PCI-E 3 connection, but as the Gen 3 lanes are linked with the upcoming Ivy Bridge CPUs, you will have to upgrade your motherboard’s BIOS to recognize and communicate the new standard without issues.
Most current motherboards only feature PCI-E 2.0 switches (a notable one being NVIDIA’s NF200 for “True SLI”), so when an Ivy Bridge CPU that has PCI-E 3 capabilities is plugged in, only eight lanes (out of the full 16) will actually function.
Motherboards with multiple PCI Express slots have the most up-to-date switch chips from vendors like Pericom or PLX to actually support the full Gen 3 bandwidth availability on NVIDIA SLI and/or AMD’s CrossFireX multi-GPU configurations. Many older motherboards that claim they are “Gen 3” ready are just hiding behind the fact that they are compatible with Ivy Bridge CPUs and aim to take advantage of consumers uneducated on the technical aspects behind this technology.
This whole “PCI Gen 3 Ready” messaging can be considered a marketing gimmick because while you are technically getting to use your new PCI Express Gen 3 peripherals (read: ensuring compatibility), you are only able to utilize half of the theoretical bandwidth. Adding to the confusion is a lack of benchmarking data available, meaning users are being divided with even more ambiguous information from what is considered “true” Gen 3.
Trying to keep up with the latest technology always seems like a futile effort, but nobody wants to feel buyer’s remorse from having missed out on the possibility of significant upgrades by not waiting. The methodology behind pushing PCI-E 3 was more to grab the mainstream market to “buy now” instead of waiting, but it seems we are still waiting for PCI-E 3 to show up on graphics cards and PCI-E SSDs. We can definitely hope that once they come to the market, the blistering fast speeds we were promised will show up as well.
As more boards are touting the Gen 3 readiness and support, just make sure you are at least going with a board that has the proper switch chips ready for you to take advantage of it when you can.