PCIE x1 to PCIE x16 doubled up, non powered, on 4x 7970s, works fine. PIC

[baritus]

Two cards 7970's on motherboard, two others using two risers connected to each other.

Powered risers what?  

No need for em

[Rawted]

Powered risers are useful because pcie1x only supports 25w, and 16x supports 75w. Most higher end GPUs take advantage of this, and most everything pciex16 that uses only 25w is non-gpu. If you use a shitty mobo/cut corners, you'll burn out your slots. Not sure what the point of this thread is, as thousands have done this in the past (i have 4 rigs myself running on plain risers).

[Bitsaurus]

Run those cards at 700MH/s or 720KH/s for a month and I guarantee you the extenders will burn or start to fail.  Watch them turn brown or black at the PCB solder points.

[tom_o]

Run those cards at 700MH/s or 720KH/s for a month and I guarantee you the extenders will burn or start to fail.  Watch them turn brown or black at the PCB solder points.

Yeah I was thinking that. Mmmmm two amps down a ribbon cable not a good idea.

[baritus]

It's been running 2 months and a half now. Overclocked as much as I can. Runs 24/7 at 730+khs no problem. Those same cables mined for a year before rig also..

[Rawted]

It's been running 2 months and a half now. Overclocked as much as I can. Runs 24/7 at 730+khs no problem. Those same cables mined for a year before rig also..

That's super, you've been lucky. However, the point you're not understanding is that it can and will cause problems. You ignoring the issues doesn't make them invalid.

[Eastwind]

For bitcoin mining, it might be OK. For LTC mining, it is better to have powered risers, especially for 7950. 7970 might not be a problem as it draws little from PCIE slot.

[ReCat]

What does it matter, anyways? Don't the GPUs pull power from the GPU power plug?

[MrBilling]

What does it matter, anyways? Don't the GPUs pull power from the GPU power plug?

Might be wrong but pretty sure that:


The GPU is powered from the PSU plug.


But the RAM on the card is powered from the PCIe slot (ie the mobo).


That's why LTC mining needs risers more than BTC mining.  LTC mining uses the GPU RAM more.

[MrBilling]

But either way this thread is pointless.


What I dont think alot of people understand is that shit will work without powering the risers most of the time.  The whole point in powering the risers is so that after you run the rig 24/7 forever the mobo doesnt burn out from pushing so much power for so long.


The motherboard is not designed to be run at 100% load 24/7.  If you do some searching on here you will find people who have had theyre ATX 24 pin connector blow and turn black.  Or other parts on the mob will blow.

[massnerder]

Yep!  I set a motherboard on fire using non powered risers with 7950s.... got 2 of them powered and all is well, probably going to make them all powered soon just for long term stability    It took less than an hour for the board to give out on non powered risers when I first made that mistake....

[taenaive]

I see he is running gigabyte cards. Most of new gigabyte cards seems to run fine without powered risers. someone should check the gigabyte's circuit board to see if it provides the power to the pins. older cards didn't have much power available from the card's power source. these days, It might provides  100% power from the card's power source (if you have a good PSU).