Topic: Noob Question About Power Plugs to GPUs (Read 343 times)

According to my knowledge there are 1200 or even 1600 watt PSUs available which provide sufficient connectors for 6 cards. By my experience you must however use ONE PSU to provide power for the mainboard, all risers and harddisc/SSD. GPUs itself can be powered by a second PSU. For example I have a rig with 10 RX580 GPUs. Mainboard, risers, SSD and 5 GPUs are lowered by a 1200 PSU which draws around 950 watt from the wall. the other 5 GPUs are on a second 1200 PSU which draws around 450 Watt from the Wall.

 The power draw is ALWAYS split between the two - the question is how does the card decide to do the split, which seems to be a "we're not talking" thing from the card makers, but a lot of testing seems to indicate that most cards use the PCI-E bus power draw as a priority over the PCI-E power connectors.

 It might also be, depending on the card, that certain parts are pulling from the bus (memory and fans perhaps) while the GPU pulls from the power connnectors - or even might be split by PHASE of the power conversion circuitry.

I love to get advice from someone who knows the research!

Took your info and found a great page with the specs on most connectors http://www.playtool.com/pages/psuconnectors/connectors.html.

Looking at the back of the EVGA SuperNova P2 1000w:

https://i.imgur.com/43x131I.jpg

Each of the VGA's are 8-pin out (rated at 336 watts per) = so splitting should be 168 watts per split (I called EVGA and they confirmed at least 300 watt per VGA output).
So I'm probably safe on a Y-Splitter keeping less than 160 watts per (and I'm at 126 max).

For the riser you are dead on, SATA is really a bad idea.
That being said, each SATA/PERF port puts out a max 75 watts (interchangeable) so theoretically, each port (4 SATA/2 PERF) 6-pin connector would support a PCI-e riser.
I could get 6-pin to Molex connectors and 'probably' be ok.

The final issue is total wattage, and my question to anyone who knows.
If a card is limited to 126 watts (using SimpleMiner), where does the power for each card come from?
Is it a mix from VGA and the PCI-e riser? Something like 100 watts VGA and 26 watts from PCI-e riser?

Or, is the power to the card considered from the VGA connector, and they PCI-e is separate power.
If they are separate, then I'm doomed with a 1kw PSU.
That would be 780 watts (230x6) for VGA + 450 watts (75x6).

Can anyone confirm if the total GPU card power is split between the PCI-e and VGA, or are they unique and separate?

 At the power level you are looking at, you could probably get away with using one of those splitters safely.

 Using SATA to power a riser AT ALL is dangerous - the PCI-E spec calls for up to 75 watts draw at 12VDC from the PCI-E bus (and some cards are KNOWN to exceed that spec on spikes by 5-10 watts), while the SATA power connector ITSELF is only rated for 54 watts of 12VDC draw.

 MOLEX connectors are rated for 156 watts - which is quite safe for powering a riser.

 At 126 watts per card, I'd be hesitant to run even 6 cards from that EVGA P2 1000 - 6 cards at the 110 or less power level should be fine, but it depends in part on how much power the rest of your system draws. If the total power draw is under 800 watts should be fine (that will read more like 860 at the wall due to PS inefficiency).

 I might be mistaken on the FTW since I don't actually have one - I am DEFINITE they have 2 power connectors, but thought it was an 8 + 6 not a dual 8.

I'd like to go the PSU route, but stuck with this EVGA 1000w P2 until I can upgrade.
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So I think for providing power to the cards - a 6-pin to 6+2 cable is the answer - then I can get the extra power cables.
The remaining issue is how to get power to all the Risers. If the PERF (peripherals) output on the PS will power a riser, then I have 4 SATA and 2 PERF.

Is there any reason to believe that 2 SATA to MOLEX cables can't run from one SATA cable to PS?
Then I can run two PCI-E risers off of 1 SATA PS connection.

I don't know i haven't done it that way for a while because it's has some kind of issue that the Sata cable might burn out due to they don't supply enough power that the GPU can need, which is a debate thing for some.

I don't use SATA plugs other then for ssd's, i use raiser cards  with pcei express plug on the raiser and plug them directly into the server psu with pcei cables. when some one on the forums said it's safe to plug it all directly into the Server Psu with break out boards and pcei cables, it does seem safer to me.  i all ways wanted to do it that way and not use the sata plug other then for SSD.
https://www.amazon.com/gp/product/B073RBP3V6/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

like this raiser

an the 1000 watt is fine for about 7 cards maybe 8 ,beyond 8 might be pushing the limits .  i use 2400 watt server psu's per rig i know it's over kill but i can plug more cards per rig if i want that way.

Thanks both for answering (I've set my current rig based on reading several of your posts @QuintLeo).
I've got each set to +200, +700, 126w, 70 for temp, and 52% Fan Speed (Averaging 510 Sols/s per card thanks to you!)

Checked again. Looks like the FTW2 has (2) 8-pin (6+2) on each 1070 ti.


So couldn't I use PCI-E Dual 8-Pin (6+2 Pin) Y-Splitter to each card?
Something like this: https://www.amazon.com/PCI-Express-Y-Splitter-Adapter-Converter-Gaming/dp/B004PBJARO

Total power would not exceed 756watts.
Is there a max wattage on each VGA out of the EVGA 1000 P2?

@toptek, the SATA splitters offer three outputs - what is the issue with 2 cards per SATA output on PS?

my EVGA 1070 ti has one 8  pin peci  plug.

I have the EVGA GeForce GTX 1070 Ti SC GAMING so

QuintLeo is right


MY 1080 has 2




form what the video shows hes using one splitter per card and you still need to power the pcei raisers cards, i don't use the power plug on the MB sense i use powered raiser cards, you don't need to use the four pin power plugs on the MB you can but i don't think it mater much unless your not using powered raiser cards.

I don't use ATX pSU i use server PSU with a DC 12V 160W 24Pin Pico ATX Switch that only powers the MB and SSD an power the EPS plug on the MB plugged directly into the PSU with a cable i made from idea's off the forums here.

I've never seen an EVGA 1070 ti that has 2 *6* pin connectors - the SC has a single 8-pin, the FTW has an 8 + 6.

 Yes, you DO need to power both on EVGA cards that have both, or the card BIOS will complain about it and not let you use the card at all.

 VoskCoin was using the SC model in his 6 card rig, and settings set for high efficiency (106 watts or so per card).

That's what I thought, but if you watch VoskCoin, he uses one 1000 watt EVGA Gold to power 6 cards.
https://youtu.be/QBmZG4pnr6A

So is he splitting each 6 pin to (2) 8 pins?

NVidia gpus need to have both powered to run the only options you have are to get a high wattage server psu with a breakout board that supports 12 to 14 cables OR the only other option is to get 2 atx power supplies and a add2psu to turn on the second psu, but that just adds another failure point and costs bit more than the server psu method

I have a question about powering GPU's, that's likely ridiculously simple.

I have 6 EVGA 1070 TI's and each has two 6 pin inputs going to it. If I'm powering these off an EVGA 1000 watt P2 power supply, do run two to 6 pins to every GPU? If I do that, then I don't have enough 6 pins for every card. I.E, I'd have two 6 pin connectors off each PS output to one card. Only allowing me to connect 3 cards. How do I get the 12 connections I need for the GPUs off the 6 connector PS?

Thanks!