Running PCIe 3.0 Graphics Card on PCIe 2.0?

I'm strongly considering a P9X79 WS MOBO for the 40-48 PCIe lanes it has available (depending on who you are talking to; I want to run a GPU, an LSI Internal SATA/SAS 9211-8i 6Gb/s PCI-Express 2.0 RAID Controller Card, a couple of TV tuners and a WiFi card). Because of space constraints in the case, the graphics card has to be kept down to a certain length to keep it from getting into the HDDs (please don't suggest a larger case; I just don't have room for it not to mention I'm a handicapped senior citizenn and need to keep weight down as much as possible). The card at the top of my list is a MSI R7850 Twin Frozr 2GD5/OC Radeon HD 7850 2GB 256-bit GDDR5 PCI Express 3.0 x16. Even though the MOBO's PCIe x16 slots are rated for PCIe 3.0, the most I can get on it is PCIe 2.0 because the only CPUs available for the LDA2011 socket on it, the Sandy Bridge E CPUs, will support only PCIe 2.0. An Ivy Bridge E for the 2011 socket won't be available until later this year, assuming Intel doesn't change their minds.

This PC will be used for office applications, basic photo editing, data storage (my books, music, movies ripped from DVDs and BDs, and personal reords), web surfing, listening to music, and watching movies (no gaming; I'm too old and slow). Although I'll initially just be running a single 22" monitor (1680 x x1050) and a 32" TV, I eventually want to replace the monitor with three 23" monitors (1920 x 1200). Would this graphics card be able to handle that load without too much of a performance loss even though it is running on on PCIe 2.0 x16?

PCIe 3.0 is still irrelevant at this point, there is simply no current card that can effectively make use of the full bandwidth of 2.0 let alone 3.0. It is overrated and offers no real life performance advantage over 2.0. Running any PCIe 3.0 card in a PCIe 2.0 slot will not affect performance, the benefits of PCIe3.0 are only visible while running intensive applications with a multi-GPU setup.

Thanks!

Lady Fitzgerald said:

Even though the MOBO's PCIe x16 slots are rated for PCIe 3.0, the most I can get on it is PCIe 2.0 because the only CPUs available for the LDA2011 socket on it, the Sandy Bridge E CPUs, will support only PCIe 2.0. An Ivy Bridge E for the 2011 socket won't be available until later this year, assuming Intel doesn't change their minds.

While Intel only lists PCI-E 2 support in the basic processor specs:

ARK | Intel® Core

However, my Asus P9X79 Pro has a Gen3 setting in the BIOS (uEFI) setup. My current graphics card is a GTX 680. The nVidia drivers set the rate to PCI-E 2, because nVidia doesn't certify PCI-E 3 on the X79 chipset, but there's a patch from them that turns on PCI-E 3. CPU-Z shows the change, and the video card bandwidth benchmark in SiSoft SANDRA confirms it.

AMD's drivers will use PCI-E 3 without any modification. (I've had a 7970 in the system.)

The P9X79 WS has the same BIOS settings. I presume that it'll support PCI-E 3 data rates just like the Pro.

Having said that, PCI-E 3 X16 is supposed to offer very little advantage over PCI-E 2 , with the possible exceptions of GPU computing applications and very demanding games.

So: PCI-E 3 doesn't matter, but you'll have it anyway.

Thanks for that update.

There's not much point to it really. If I am not mistaken the only thing that can completely saturate a PCI-E 2.0+ slot is something like an LSI Warpdrive. I'm going to go out on a limb here, but i'm pretty sure you don't have one =3

VistaKing said:

Hi Lady see if this link could help How to enable PCI-E 3.0 in Windows 7

Your board does support PCI X16 3.0 . Try the black or blue slots

I know the board does. It's the CPU (i7-3930K Sandy Bridge E; Ivy Bridge isn't available for the X79s yet, if ever) that's supposed to not support it. Will the directions in your link still work with a Sandy Bridge E?

The GPU card is destined for the top (blue) slot. I don't have the parts yet; I just ordered them today when I noticed today that NewEgg ran out of the RAM sticks I wanted (the only ones on ASUS' approved list) and Amazon had only two left. The board, cooler, RAM, CPU, and GPU will be trickling in next week. I caught the TIM on sale (free if I don't have any trouble with the rebate) which should be delivered tomorrow and it was delivered and already have the SSD, two data storage HDDs (will buy more, up to six total, as I need them) and extra HDDs for backups, cables, case (already prepped except for one Molex cconnector that needs pins which I will pick up tomorrow), PSU, and an el cheapo DVD drive I picked up for a dummy to use for making the cables (I had three dead 3.5" HDDs and a somewhat dead 2.5" HDD I also used for making up cables) and will replace with a BD drive later. You can see the case here starting at post #1029.

Jerlys said:

There's not much point to it really. If I am not mistaken the only thing that can completely saturate a PCI-E 2.0+ slot is something like an LSI Warpdrive. I'm going to go out on a limb here, but i'm pretty sure you don't have one =3

LOL! My daughter might be interested in the warp drive (she was a trekker back when she was in her twenties; she's pushing 40 now). The only LSI part I'll eventually be using is this one (probably in slot 4). The GPU was the only one I was concerned about. The SATA controller will be only x8 and the two TV tuners and the WiFi card will be only x1 each (all PCIe 2.0 and installed below the SATA card).