PCI Express 3 - Gigabyte vs MSI
Are you really Ivy Bridge ready?
Published: 12th September 2011 | Source: OC3D |
So What's It All About?
One of the big bits of news floating around at the moment is the compatibility of motherboards with PCI Express 3, which is part of the forthcoming Ivy Bridge processor package.
Indeed this compatibility is causing quite a stir. Initial reports were that a BIOS upgrade would enable PCIe 3 compatibility on your current P67/Z68 chipsets and, to a certain degree, this is true. MSI have been releasing quite a few documents of late pointing out that whilst it is possible to allow the use of PCI Express 3 hardware, a simple BIOS flash doesn't actually provide the bandwidth increases which are the point of PCIe 3 in the first place. Now although MSI seem to be going out of their way to point out that Gigabytes claims of compatibility are false, when we read the reports of the BIOS updates we never thought that Gigabyte meant it would allow the 32GB/s bandwidth. After all bandwidth doesn't just appear out of the blue does it. Huge press releases based upon potential misunderstandings seem a bit of an over-reaction to us.
Think of it like USB 3.0. You can put your USB 3.0 device into a USB 2.0 port and it will work perfect fine. It's compatible. What it wont do is give you the USB 3.0 bandwidth. PCI Express 3 compatibility is pretty much the same idea. Your PCIe 3 GPU will work, but it'll work at PCIe 2 bandwidth levels.
Of course whether you believed that the full benefits of PCIe 3 could be provided with a simple BIOS update is a different matter, but with the forthcoming Gen3 motherboards from MSI they are taking great pains to point out that their new range is gives the full 32 GB/s PCI Express 3 bandwidth, as opposed to the 16 GB/s but compatible option available from Gigabyte BIOS upgrades. Bandwidth is, as we all know, vital. Anyone who has run two high-end cards in SLI/Crossfire and had them limited to PCIe x8 will be aware how vital having huge amounts of bandwidth available to send data to the card can be. PCI Express 3 has twice the bandwidth of PCIe 2 available to it. Place your PCIe 3 GPU (when they are released) into a true PCIe3 board and it'll be fed by a full 32 GB/s. Place it into a compatible board and it'll work, but only at the current PCIe 2 speed.
If that isn't enough, because the P67/Z68 chipset isn't compatible with PCI Express 3, MSI have had to go away and get their own chip to provide sufficient PCIe lanes for you to run more than a single card, the Pericom 3412 and 3415 chips. Put two PCIe 3 cards in a board that's merely compatible, rather than has official support, and they'll just run as a single card. So these switches are a vitally important element.
It would be very easy at this point to wonder what Gigabyte have to offer with their Legacy BIOS and vague marketing about compatibility vs actual bandwidth, but we've been hearing some strong rumours of late that potentially muddy the waters even further, and now they are being reported elsewhere too we thought we'd give you a chance to know what we know, and perhaps tell us what you think. The very thing we've long complained about the Gigabyte boards, their Legacy BIOS, is something we've often spoken to them about and they've said that it's just a business decision based upon the fact they were unhappy with the current UEFI BIOS and prefer the bulletproof nature of the Legacy one. This now has the happy coincidence that because current UEFI BIOS are incompatible with Ivy Bridge and any current boards require a RTB flash to make them able to accept Ivy Bridge processors, Gigabyte have unexpectedly ended up with potentially the only boards on the market that are Ivy Bridge ready.
So on the one hand you have MSI saying their motherboards are truly Gen3 and Ivy Bridge ready, but as we understand it that is a moot point because the UEFI BIOS means you can't use Ivy Bridge chips in them. And on the other hand we have Gigabyte with a Legacy BIOS that will accept Ivy Bridge CPUs, but they aren't actually full bandwidth PCIe 3 ready.
Now we're not going to stick the boot in to either company because until Ivy Bridge and the PCIe 3 GPUs arrive we really can't tell how much truth there is to all of this. But if we assume all of the above is true and valid, then it appears the Gigabyte Z68 G1.Sniper 2 is the only Ivy Bridge ready motherboard around as it has genuine PCI Express 3 support and the Legacy BIOS that hasn't got issues with Ivy Bridge.
We can't wait to see how this will all pan out, and we're certain that the mud-slinging from both sides will only intensify as the release date for the 22nm CPUs approaches. Probably the most important thing to remember through all this is that PCI Express 3 cards don't exist yet, and so nobody has been able to prove if any boards at all work.
Let us know what you think in our Forums.