Gigabyte Sets Record Straight on PCIe 3.0 Support

[RazberyBandit]

None of this bandwidth crap really matters because the cards can't make use of PCIe-3.0's additional bandwidth capacity anyway. GPUs still can't fully saturate 16-lanes of PCIe-2.0 available bandwidth. It's like building a 5-mile oval test track for 200+ MPH supercars, but only taking cars capable of running flat-out at 75 MPH to drive on it.

Honestly, it's not the additional bandwidth that PCIe-3.0 (and for that matter, 2.1) brings to the table that's the real benefit. The real benefit is the additional through-the-slot power capacity.

PCIe 2.1 and 3.0 slots can supply twice as much power through the PCIe slot itself than a 2.0 slot can. If board makers would actually bother to fully deploy PCIe-2.1 or 3.0 slots, then every GPU powered by a single PCIe 6-pin cable wouldn't need a cable at all. Every GPU powered by 2x PCIe 6-pin cables would only need one. Take a moment to think about all the mid-range gaming and entry-level enthusiast GPU cards that could benefit from that. AMD saw the light and has made every board since its 5000-series PCIe 2.1. Nvidia didn't, and in failing to do so, actually held back PCIe progress.

I can recall (but cannot find so I can link) Tom's doing some sort of feature about a Powercolor microATX or ITX 'cube' build into which Powercolor was able to shove a special HD5770 (no PCIe power cable required) because they specifically used a PCIe 2.1 slot on the motherboard.

 

[josejones]

"None of this bandwidth crap really matters because the cards can't make use of PCIe-3.0's additional bandwidth capacity anyway. GPUs still can't fully saturate 16-lanes of PCIe-2.0 available bandwidth."

This misses the point and is not a good argument IMV. I'm more interested in the new, next generation platform not just GPU's. There will be no PCIe 3 products if they don't come out with motherboards that include PCIe 3 support. There are many benefits to PCIe 3.0.

Besides, AMD/Radeon has already announced that their new 7000 series GPU's will support PCIe 3.

AMD Radeon HD 7000 GPU Series to Feature PCI Express 3.0 Support

So, AMD PCIe 3.0 motherboards should be due out anytime soon.

 

[RazberyBandit]

Jose. I want the platform to develop, too. I wish it were as simple as sticking a PCIe 3.0 slot on a motherboard and calling it a day, but it's so much more complicated. And yes, I know PCIe 3.0 carries more benefits than simply increased bandwidth, but I chose to pick on that one portion. Just because I only discussed one part of it doesn't make my point invalid.

AMD wanted board makers to fully adopt all the benefits of PCIe 2.1 when they introduced 2.1 GPUs. How did that fair? It didn't happen - not on a single board. Why? Nvidia didn't follow suit with its GPUs, and it still hasn't. That forced AMD to continue building GPU boards with PCIe power connectors so they could function in PCIe 2.0 slots.

PCIe 3.0's implementation story is following a different path. Since motherboard makers have already announced their intentions to adopt it, Nvidia will have little choice but to do so or face falling behind. Still, the fact remains that no 2.0/2.1 GPU can saturate the 5 GT/s sample rate a 16-lane PCIe 2.0 slot offers. Is the next generation of GPUs going to require PCIe 3.0's 8 GT/s sample rate? Barring an immediate major breakthrough, not likely. Some of the highest-performing GPUs might, but the vast majority of GPUs will continue to utilize less than 2.0's maximum sample rate.

When speaking specifically about the bandwidth of PCIe, it immediately reminds me of the change from SATA-II to SATA-III; bandwidth doubled, but standard hard disks didn't need it. Hell, they still can't scratch the peak of SATA-II's available bandwidth. Only SSD's can actually make use of the additional bandwidth the SATA-III interface provides. Unless there's a drastic change in GPU design, I expect PCIe 3.0's bandwidth results to mirror what happened with hard disks with GPUs still incapable of utilizing any of the additional bandwidth PCIe 3.0 offers.

 

[Avro Arrow]

As usual with these things, it's all "Much Ado About Nothing". Current cards are only really fast enough to use PCI-Express 2.0 x8 and here we have griping about BS. Well, since PCI-Express 3.0 is supposed to have double the bandwidth of PCI-Express 2.0 then I suppose that my 990FX motherboard that runs Crossfire natively at PCI-Express 2.0 x16/x16 has exactly the same bandwidth as the new Intel-based PCI-Express 3.0 motherboards that run Crossfire at PCI-Express 3.0 x8/x8. PCI-Express 3.0 has arrived to early to really make a difference because the cards aren't even really ready to use all of it yet. I give it another 2-3 years before the cards actually manage to use all of PCI-Express 2.0 x16 because right now they only use up to half of that.