Running PCIe 3.0 Graphics Card on PCIe 2.0?

[Lady Fitzgerald]

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?

 

[yowanvista]

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.

 

[Lady Fitzgerald]

Thanks!

 

[bobkn]

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.

 

[Lady Fitzgerald]

Thanks for that update.

 

[VistaKing]

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

 

[Jerlys]

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

 

[Lady Fitzgerald]

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.

 

[Lady Fitzgerald]

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).

 

[VistaKing]

I'm on the rog.asus forum and people on there had no issue running there graphic cards with pci x16 3.0 with 3960x or 3930k . There graphic cards were Radeon HD 7970 .

 

[bobkn]

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.

Maybe I wasn't clear. The I7-3930k provides PCI-E 3 on a P9X79 Pro, even though Intel doesn't officially support it. There's nothing that you need to do to turn it on, other than leave the BIOS settings at their default Gen3 values. I guess that Intel built-in the capability, but decided not to certify it.

(I need to use an nVidia utility to turn on PCI-E 3 in their drivers for a GTX 680. Nothing like that is needed with a AMD Radeon 7970; I presume that a 7850 would be the same.)

You make your own custom cables? Neat. Most of the "cable management" enthusiasts I've seen don't go in for that.

 

[VistaKing]

Cable management enthusiasts use para cord 550 for recabling their power supply cables and others . Takes a long time to do .

 

[Lady Fitzgerald]

...Maybe I wasn't clear. The I7-3930k provides PCI-E 3 on a P9X79 Pro, even though Intel doesn't officially support it. There's nothing that you need to do to turn it on, other than leave the BIOS settings at their default Gen3 values. I guess that Intel built-in the capability, but decided not to certify it...

OK. Not doing something is something I can do (wait a minute; what did I just say?).

...You make your own custom cables? Neat. Most of the "cable management" enthusiasts I've seen don't go in for that.

Mayhap I tend to be anal?

All seriousness aside, I didn't have much choice with the case I chose. The stock PSU cables were too long or too short, had too many or not enough connectors, ran in the wrong direction (in the case of the the SATA power cables) and/or the wires weren't heavy enough (when dealing with 5v and 12v, even a small voltage drop can be a problem). The hot swap bays each had to be on their own PSU cables to avoid having other drives drop out when drives were inserted. Trying to use the stock cables would have been a nightmare that would have resulted in still getting a space eating, airflow restricting rat's nest no self respecting rat would deign to live in. Hence, custom cables.

 

[Lady Fitzgerald]

Cable management enthusiasts use para cord 550 for recabling their power supply cables and others ...

Are you thinking of lacing instead of sleeving?

Lacing:

Sleeving:

...Takes a long time to do .

Yeah, I noticed that. :sarc: Modular PSUs simplify the task a bit.