Bitcoin Forum

Do I really need powered risers if I got a mobo that supports 4x pcie16x?

Talking about connecting 4x 7950

Powered riser is not essential for BTC mining. But, it is not economical to use GPU for BTC mining. It is better to mine LTC etc. So powered riser is important if you want to use more than 2 GPUs in a PC.

Only if the motherboard you're using doesn't have extra power (molex) near the PCI slots on the baord itself.

The risk is then burning out some pins on the ATX connector. If you have the extra power @ the slots, you're in the clear.

Well ok. But the motherboard clearly says it is capable of 4x gfx cards and the psu (1200w) have like 10 x pcie power cables ??! I dont get what powered risers does rly...Can someone explain a bit deeper?

from what I understand (which i am no expert) the motherboard is capable of supplying power to pci-e cards. every high end graphics card has one or two external power connectors anyway and typically will not run if those are not plugged in, so a powered riser is not necessary.

I could see maybe in the situation that you have 2 power connectors on your card but only plug in one, and rely on the motherboard powerline from the pci-e to provide the rest, then maybe you should use powered risers but in that situation, just take more power from the power supply rather than routing it through the motherboard.

I have 4 x 7970's running on one machine with normal non powered Risers working fine...

Almost the same here.. 3x7970 and 1x7870 all on one mobo (ASRock xtreme3) non-powered risers for 1yr+ thus far.. (1050W gold PSU)

Had another rig with 7950x3 and another 7870x1 until I re-tweaked the 7950s, at that point I didnt want to abuse my 1000w gold PSU too much.. so I took the 7870 off.. 

Okay thanks guys! I will plug my 4x7950 in today without any worries then :)

I got 3 for sale here:

https://www.bitmit.net/en/item/48342-pcie-x16-to-x16-extender-riser-cable-w-molex-connector

I use PCIe1x to PCIe1x connector for my 10 GPUs.
Fuck the police.

I run 5 x 7950 on a couple of my rigs with no issue.  4 non powered / 1 powered via molex.  They are split between an Antec 900W and Corsair 850W PSUs.  No problems with LTC mining here.

So are there any drawbacks to using powered risers? I ran my rig without using the powered connectors for a week and it seemed fine. I now have the powered connectors attached and can't tell a difference.

Currently using 3x7970s with a fourth coming online soon.

I have one of those Infrared Thermometers to see what the temps are like but don't know where to check. The 24 pin ATX connector?

https://i.imgur.com/WFILc90.jpg

Do powered risers work if you just don't plug the molex in? 

Just curious... ordered several powered and unpowered risers but haven't had a chance to play with them yet on my milk-crate.

Mine did. Asked the supplier before I did and they said plugging them in was optional.

Cool.  Thanks for that info!  I am still anxious about getting all these video cards working without having to use a 2nd PSU.

Everyone says 850W should be fine but I am running out of plugs and all the adaptors I am trying are not working!

You should used powered risers regardless of how many video cards you are using. You could safely run 2-3 cards without powered risers. I made the mistake of not using powered risers because other people said I could run five gpus without them. Well, my mother board had a molex connection for pci-e slots and I had ocz gold psu. well, my cable for my psu burnt out, and somewhere along the line i had to send back my gpu for a replacement.

Use powered risers if you want to power more than 2 or 3 three cards. Do not listen to those who say you do not need them. You could probably get them for around 8-12 each. Or even 6 if you get them directly from China.

Yes you can run 5 GPU without them but it depend of what GPU model. It also depend of the motherboad you use.

I have 10x 6770 but each consume about 90W (undervolted). If you try 5x 7990 ofc it's gonna burn  ::)

I tried 5x 7950. even 4 made it burn

A graphics card takes power from the on card power connectors for the GPU. It takes power for the on-board video RAM from the PCI-E bus connection.

That is fine for games and for Bitcoin mining but not so good for Litecoin and other scrypt based alt-coins. Scrypt mining hits the graphics card RAM with a  much higher load than gaming or Bitcoin mining. Without powered risers, you will be drawing more current from the motherboard than would be the case for most uses of graphics cards. That is when you can get into trouble if you do not have powered risers.