PCI-e bandwidth/capacity limitations

A forum for discussing FAH-related hardware choices and info on actual products (not speculation).

Moderator: Site Moderators

Forum rules
Please read the forum rules before posting.
SteveWillis
Posts: 409
Joined: Fri Apr 15, 2016 12:42 am
Hardware configuration: PC 1:
Linux Mint 17.3
three gtx 1080 GPUs One on a powered header
Motherboard = [MB-AM3-AS-SB-990FXR2] qty 1 Asus Sabertooth 990FX(+59.99)
CPU = [CPU-AM3-FX-8320BR] qty 1 AMD FX 8320 Eight Core 3.5GHz(+41.99)

PC2:
Linux Mint 18
Open air case
Motherboard: ASUS Crosshair V Formula-Z AM3+ AMD 990FX SATA 6Gb/s USB 3.0 ATX AMD
AMD FD6300WMHKBOX FX-6300 6-Core Processor Black Edition with Cooler Master Hyper 212 EVO - CPU Cooler with 120mm PWM Fan
three gtx 1080,
one gtx 1080 TI on a powered header

Re: PCI-e bandwidth/capacity limitations

Post by SteveWillis »

I'll just mention that my system/motherboard won't recognize all 4 1080 TIs unless I use powered risers. I'd love to find some good ones.
Image

1080 and 1080TI GPUs on Linux Mint
bruce
Posts: 20910
Joined: Thu Nov 29, 2007 10:13 pm
Location: So. Cal.

Re: PCI-e bandwidth/capacity limitations

Post by bruce »

Unpowered risers draw power from the motherboard and the total for all PCIe slots is limited to 75w. I'm surprised that you can run several.

Even with power to the external power plug, I suspect that some power is drawn from the slot itself -- and I think you've just confirmed that. I have no idea which power would be drawn from the powered riser but it's apparently not zero.
Aurum
Posts: 296
Joined: Sat Oct 03, 2015 3:15 pm
Location: The Great Basin

Re: PCI-e bandwidth/capacity limitations

Post by Aurum »

SteveWillis wrote:I'll just mention that my system/motherboard won't recognize all 4 1080 TIs unless I use powered risers. I'd love to find some good ones.
May I suggest a MB with a supplemental power plug?
https://www.newegg.com/Product/Product. ... 813128772R
In Science We Trust Image
SteveWillis
Posts: 409
Joined: Fri Apr 15, 2016 12:42 am
Hardware configuration: PC 1:
Linux Mint 17.3
three gtx 1080 GPUs One on a powered header
Motherboard = [MB-AM3-AS-SB-990FXR2] qty 1 Asus Sabertooth 990FX(+59.99)
CPU = [CPU-AM3-FX-8320BR] qty 1 AMD FX 8320 Eight Core 3.5GHz(+41.99)

PC2:
Linux Mint 18
Open air case
Motherboard: ASUS Crosshair V Formula-Z AM3+ AMD 990FX SATA 6Gb/s USB 3.0 ATX AMD
AMD FD6300WMHKBOX FX-6300 6-Core Processor Black Edition with Cooler Master Hyper 212 EVO - CPU Cooler with 120mm PWM Fan
three gtx 1080,
one gtx 1080 TI on a powered header

Re: PCI-e bandwidth/capacity limitations

Post by SteveWillis »

Mine has that but it's just a plain molex. Still if I don't use a powered riser on at least one GPU only three get recognized.
Also I was kind of limited in choices as I wanted AMD with at least 4 16X pcie slots
Image

1080 and 1080TI GPUs on Linux Mint
Aurum
Posts: 296
Joined: Sat Oct 03, 2015 3:15 pm
Location: The Great Basin

Re: PCI-e bandwidth/capacity limitations

Post by Aurum »

Hmm, that's odd. Sometimes a molex pin pushes back out and does not make electrical connection. What's the MB model? Are all 4 folding now?
In Science We Trust Image
Aurum
Posts: 296
Joined: Sat Oct 03, 2015 3:15 pm
Location: The Great Basin

Re: PCI-e bandwidth/capacity limitations

Post by Aurum »

Has anybody ever tried this EVGA Power Boost :?:
https://www.evga.com/products/product.a ... MB-PB01-BR
In Science We Trust Image
SteveWillis
Posts: 409
Joined: Fri Apr 15, 2016 12:42 am
Hardware configuration: PC 1:
Linux Mint 17.3
three gtx 1080 GPUs One on a powered header
Motherboard = [MB-AM3-AS-SB-990FXR2] qty 1 Asus Sabertooth 990FX(+59.99)
CPU = [CPU-AM3-FX-8320BR] qty 1 AMD FX 8320 Eight Core 3.5GHz(+41.99)

PC2:
Linux Mint 18
Open air case
Motherboard: ASUS Crosshair V Formula-Z AM3+ AMD 990FX SATA 6Gb/s USB 3.0 ATX AMD
AMD FD6300WMHKBOX FX-6300 6-Core Processor Black Edition with Cooler Master Hyper 212 EVO - CPU Cooler with 120mm PWM Fan
three gtx 1080,
one gtx 1080 TI on a powered header

Re: PCI-e bandwidth/capacity limitations

Post by SteveWillis »

Aurum wrote:Has anybody ever tried this EVGA Power Boost :?:
https://www.evga.com/products/product.a ... MB-PB01-BR
I tried one and the motherboard would never boot again. Had to replace it
Image

1080 and 1080TI GPUs on Linux Mint
SteveWillis
Posts: 409
Joined: Fri Apr 15, 2016 12:42 am
Hardware configuration: PC 1:
Linux Mint 17.3
three gtx 1080 GPUs One on a powered header
Motherboard = [MB-AM3-AS-SB-990FXR2] qty 1 Asus Sabertooth 990FX(+59.99)
CPU = [CPU-AM3-FX-8320BR] qty 1 AMD FX 8320 Eight Core 3.5GHz(+41.99)

PC2:
Linux Mint 18
Open air case
Motherboard: ASUS Crosshair V Formula-Z AM3+ AMD 990FX SATA 6Gb/s USB 3.0 ATX AMD
AMD FD6300WMHKBOX FX-6300 6-Core Processor Black Edition with Cooler Master Hyper 212 EVO - CPU Cooler with 120mm PWM Fan
three gtx 1080,
one gtx 1080 TI on a powered header

Re: PCI-e bandwidth/capacity limitations

Post by SteveWillis »

Aurum wrote:Hmm, that's odd. Sometimes a molex pin pushes back out and does not make electrical connection. What's the MB model? Are all 4 folding now?
I had the same experience on two different rigs using the same MB It's kind of out of date but I liked it. ASUS Crosshair V Formula-Z Republic of Gamers, AM3+, AMD Motherboard

The one I killed was a different board
Image

1080 and 1080TI GPUs on Linux Mint
SteveWillis
Posts: 409
Joined: Fri Apr 15, 2016 12:42 am
Hardware configuration: PC 1:
Linux Mint 17.3
three gtx 1080 GPUs One on a powered header
Motherboard = [MB-AM3-AS-SB-990FXR2] qty 1 Asus Sabertooth 990FX(+59.99)
CPU = [CPU-AM3-FX-8320BR] qty 1 AMD FX 8320 Eight Core 3.5GHz(+41.99)

PC2:
Linux Mint 18
Open air case
Motherboard: ASUS Crosshair V Formula-Z AM3+ AMD 990FX SATA 6Gb/s USB 3.0 ATX AMD
AMD FD6300WMHKBOX FX-6300 6-Core Processor Black Edition with Cooler Master Hyper 212 EVO - CPU Cooler with 120mm PWM Fan
three gtx 1080,
one gtx 1080 TI on a powered header

Re: PCI-e bandwidth/capacity limitations

Post by SteveWillis »

SteveWillis wrote:
Aurum wrote:Has anybody ever tried this EVGA Power Boost :?:
https://www.evga.com/products/product.a ... MB-PB01-BR
I tried one and the motherboard would never boot again. Had to replace it
However I Googled a lot and never found another report of that
Image

1080 and 1080TI GPUs on Linux Mint
foldy
Posts: 2061
Joined: Sat Dec 01, 2012 3:43 pm
Hardware configuration: Folding@Home Client 7.6.13 (1 GPU slots)
Windows 7 64bit
Intel Core i5 2500k@4Ghz
Nvidia gtx 1080ti driver 441

Re: PCI-e bandwidth/capacity limitations

Post by foldy »

I know if you run fast GPUs on pcie 2.0 x1 using WINDOWS then your PPD is reduced significantly.
If you run a GTX 1070 or GTX 1080 Ti on pcie 2.0 x1 risers using LINUX, how much PPD would you get?

Can I interpret these results from @rwh202 that on LINUX you can run a gtx 1080 on x1 risers with 90% performance?
viewtopic.php?f=38&t=28847&p=292130&hilit=riser#p292130

I'm asking because coin miners typically run many GPUs using x1 risers and want to evaluate if they could run folding@home efficiently.
SteveWillis
Posts: 409
Joined: Fri Apr 15, 2016 12:42 am
Hardware configuration: PC 1:
Linux Mint 17.3
three gtx 1080 GPUs One on a powered header
Motherboard = [MB-AM3-AS-SB-990FXR2] qty 1 Asus Sabertooth 990FX(+59.99)
CPU = [CPU-AM3-FX-8320BR] qty 1 AMD FX 8320 Eight Core 3.5GHz(+41.99)

PC2:
Linux Mint 18
Open air case
Motherboard: ASUS Crosshair V Formula-Z AM3+ AMD 990FX SATA 6Gb/s USB 3.0 ATX AMD
AMD FD6300WMHKBOX FX-6300 6-Core Processor Black Edition with Cooler Master Hyper 212 EVO - CPU Cooler with 120mm PWM Fan
three gtx 1080,
one gtx 1080 TI on a powered header

Re: PCI-e bandwidth/capacity limitations

Post by SteveWillis »

My 1080 on a 2.0 x1 typically gets better than 600K PPD. my other 1080s normally get 750-800K so I'm estimating I lose about 9% on that card. Linux Mint.
Image

1080 and 1080TI GPUs on Linux Mint
foldy
Posts: 2061
Joined: Sat Dec 01, 2012 3:43 pm
Hardware configuration: Folding@Home Client 7.6.13 (1 GPU slots)
Windows 7 64bit
Intel Core i5 2500k@4Ghz
Nvidia gtx 1080ti driver 441

Re: PCI-e bandwidth/capacity limitations

Post by foldy »

@SteveWillis: Is this with USB x1 risers? Anyone tried USB risers for x1? Does USB risers hurt performance more compared to flat cable risers?
bruce
Posts: 20910
Joined: Thu Nov 29, 2007 10:13 pm
Location: So. Cal.

Re: PCI-e bandwidth/capacity limitations

Post by bruce »

IN THEORY: the ribbon cable version should be slightly faster. While the x1 bandwidth would be the same, there would be a bit more latency because the parallel bits would have to be serialized and then serialized.

The ribbon cable would be more susceptible to noise/interference but over that short distance, that's probably insignificant.

I've use both and have never measured a difference. The USB variety just "feels" better, but that's probably just my prejudice.
SteveWillis
Posts: 409
Joined: Fri Apr 15, 2016 12:42 am
Hardware configuration: PC 1:
Linux Mint 17.3
three gtx 1080 GPUs One on a powered header
Motherboard = [MB-AM3-AS-SB-990FXR2] qty 1 Asus Sabertooth 990FX(+59.99)
CPU = [CPU-AM3-FX-8320BR] qty 1 AMD FX 8320 Eight Core 3.5GHz(+41.99)

PC2:
Linux Mint 18
Open air case
Motherboard: ASUS Crosshair V Formula-Z AM3+ AMD 990FX SATA 6Gb/s USB 3.0 ATX AMD
AMD FD6300WMHKBOX FX-6300 6-Core Processor Black Edition with Cooler Master Hyper 212 EVO - CPU Cooler with 120mm PWM Fan
three gtx 1080,
one gtx 1080 TI on a powered header

Re: PCI-e bandwidth/capacity limitations

Post by SteveWillis »

@foldy, Yes with a usb riser
Image

1080 and 1080TI GPUs on Linux Mint
rwh202
Posts: 425
Joined: Mon Nov 15, 2010 8:51 pm
Hardware configuration: 8x GTX 1080
3x GTX 1080 Ti
3x GTX 1060
Various other bits and pieces
Location: South Coast, UK

Re: PCI-e bandwidth/capacity limitations

Post by rwh202 »

AFAIK, 'USB' risers should be nigh on identical to the ribbon versions.
They are not USB nor serial - it's just a cheap, convenient cable and connector type with enough conductors and shielding to support PCIE 1x.
Post Reply