New to compute GPU's: Can I run a Tesla P4 on a PCIe x4 or x1 slot?

[vile1]

Hi guys, long time lurker first time poster, I joined the F@H group when COVID hit, and recently came across some Tesla P4s and was wondering if my Asus z590 board, with only an extra x4 Connector and 2 x1's. 

Would I need to upgrade to a motherboard with multiple x8 or x16 slots? 

 

Thanks in advance! 

[mariushm]

In general, any pci-e card is supposed to run in a pci-e slot, no matter how many electrical pci-e lanes it has.  So, the card should run in a pci-e x16 slot that has only 4 pci-e lanes, or even a pci-e x1 slot. 

However, some pci-e cards may have firmware (bios) on them which refuses to enable the card if there aren't a minimum of pci-e lanes. I've heard of some SAS 8 port controllers that refused to start without a minimum of 4 pci-e 2.0 lanes (2 GB/s) or some 10 gbps network cards that wanted a minimum of 2 pci-e lanes.

 

You can get a pci-e x1 to pci-e x16 riser / adapter and have the card plugged in that riser.  You could literally CUT the edge connector to the x4 size and plug the card into a x4 slot - the pci-e edge connector on cards is designed like that, you can physically cut it, the connector has special pins to detect how many pci-e lanes are present in the slot, so if you cut the edge connector, the card and motherboard automatically detects the maximum number of lanes by the number of those special contacts in the edge connector being detected.

 

Some motherboards have special pci-e x1 or x4 slots that don't have a wall at the end of the slot and they're carefully made to not have components where the card's edge connector would sit in the air, so you could plug a x16 video card in a x1 slot with big part of its edge connector floating in the air - it's the same idea, pci-e connectors are designed like that, the card will simply run at x1 or x4 speeds.

 

[vile1]

13 minutes ago, mariushm said:

In general, any pci-e card is supposed to run in a pci-e slot, no matter how many electrical pci-e lanes it has.  So, the card should run in a pci-e x16 slot that has only 4 pci-e lanes, or even a pci-e x1 slot. 

However, some pci-e cards may have firmware (bios) on them which refuses to enable the card if there aren't a minimum of pci-e lanes. I've heard of some SAS 8 port controllers that refused to start without a minimum of 4 pci-e 2.0 lanes (2 GB/s) or some 10 gbps network cards that wanted a minimum of 2 pci-e lanes.

 

You can get a pci-e x1 to pci-e x16 riser / adapter and have the card plugged in that riser.  You could literally CUT the edge connector to the x4 size and plug the card into a x4 slot - the pci-e edge connector on cards is designed like that, you can physically cut it, the connector has special pins to detect how many pci-e lanes are present in the slot, so if you cut the edge connector, the card and motherboard automatically detects the maximum number of lanes by the number of those special contacts in the edge connector being detected.

 

Some motherboards have special pci-e x1 or x4 slots that don't have a wall at the end of the slot and they're carefully made to not have components where the card's edge connector would sit in the air, so you could plug a x16 video card in a x1 slot with big part of its edge connector floating in the air - it's the same idea, pci-e connectors are designed like that, the card will simply run at x1 or x4 speeds.

 

Nice! This is exactly what I thought, I'm hoping it works once it arrives! 

[Gorgon]

On 1/4/2022 at 1:54 AM, vile1 said:

Hi guys, long time lurker first time poster, I joined the F@H group when COVID hit, and recently came across some Tesla P4s and was wondering if my Asus z590 board, with only an extra x4 Connector and 2 x1's. 

Would I need to upgrade to a motherboard with multiple x8 or x16 slots? 

 

Thanks in advance! 

Welcome to the Fold!

 

Yes, you absolutely can run those T4s on x1 or x4.

 

A PCIe3x1 connection might limit the bandwidth on the T4s and you'd likely see a drop in performance of 10-50% under Windows (less under Linux). Of more concern is that these cards are entirely Bus powered so the whole 75W TDP would have to go through the riser's power cable so you'll want to ensure the riser has a good power connector. I'd recommend using Molex rather than SATA. (Google Mining Fires)

 

If you have a spare m.2 slot a m.2 to PCIex16 adapter would work better and give you x4 rather than x1.

 

If you want to dedicate these to folding 24x7x365 and do not want to fold on the CPUs (not really worth it) then a dedicated rig could be built at minimal cost using a used z370/470 "SLI" motherboard with x8/x8 and a Pentium Gold G4000/5000-series CPU with 4-8GB DDR4-2133 or better. I used a couple such rigs for years with no issues but upgraded as I run BOINC on the CPUs. (If your in Canada PM me)

 

For comparison here's the current GPU utilization under Linux (Ubuntu 18.04.3 LTS) for a 2070S and 2060S: