Confused about powered risers and GPU power supply

Spartan11

Prominent
Jun 30, 2017
1
0
510
Sorry this is very complicated to me, I greatly appreciate any guidance here.

I have a couple questions regarding a mining rig I am in the process of putting together.
First off, I have:
-EVGA 850 G2 (has 4 "VGA" outputs")
-Also bought Corsair rm850i (but I dont think this will work, I will explain later, I can return this if needed)
-MSI z170A krait gaming 3x motherboard (7 PCI slots, combination of PCI 3.0 slots: x16, x1, x1, x1, x8, x1, x4)
-GTX 1080 EVGA FTW (requires two 8 pins)
-GTX 1070 8 gb EVGA FTW (requires two 8 pins)
-GTX 1070 8 gb EVGA FTW (requires two 8 pins)
-Rx 580 8 gb Sapphire nitro (requires one 8 pin and one 6 pin)
-Rx 470 4 gb sapphire (requires one 6 pin)
-Rx 580 8 gb Powercolor (requires one 8 pin)
-I have several PCI 1x to 16x powered risers (right now I have 3 but I can order more)

First question:
1) I bought this dual PSU adapter, Raidmax 24 Pin 2 Way Dual PSU Adapter Cable - Control two PSUs with one button ATX Y Splitter (http://www.frys.com/product/8393337?source=google&gclid=Cj0KEQjw7dfKBRCdkKrvmfKtyeoBEiQAch0egThDFUS28vajucOei7enVnSfJR23hYwrSIXmaiXdfewaAiHQ8P8HAQ).
This thing does not fit into my EVGA PSU? My motherboard PSU slot currently has a an 18 pin and a 10 pin coming out of the PSU. The corsair PSU I also bought is set up the same way. Is there any sort of adapter I can use to use both PSU?
Alternatively, I can return the Corsair PSU and suck it up and just buy a 1200W PSU instead but this leads to my second question...

2) Any PSU I look up does not have nearly enough "VGA" ports ie the 8 pin PSU ports. Most of my cards require two 8 pin connections. Thats why I bought a second PSU in the first place. This does not even take into account the powered risers and what PSU ports I would use to power those.

3) Regarding powered risers, do I also need to provide power to the GPU via the VGA PSU ports? Ie if I have a powered riser hooked up via the molex cable, do I ALSO need to plug in the two 8 pin connectors if I put the 1080 or 1070 on the powered riser?

Thanks again if you read this far, I am new to this and really appreciate the help.
 
Solution

You do not plug that adapter cable into the PSU's modular connector...

Barty1884

Retired Moderator
1. Combining PSUs is (extremely) rarely a good idea

2. Lots of PSUs have the appropriate connectors..... but you're looking at more expensive options, and higher wattage overall.
https://pcpartpicker.com/product/QG38TW/evga-power-supply-220gs1050v1
10 x 6+2 PCIe connectors.
You need 8 x 8pins and 2x 6 pins.
So, it has the appropriate PCIe connectors, just not enough power for your rig.

Your GPU power draw can be north of 1100W at max load
1080 = 180W
1070 = 215W
1070 = 215W
580 Nitro = 225W
470 = 120W
580 PC = 185W

Depending on the balance of your system, and to maintain decent efficiency levels.... you probably want 1500W+ from a single, quality PSU (incidentally, likely cheaper than the 2 PSUs you bought)

https://pcpartpicker.com/product/LbtWGX/evga-power-supply-220p21600x1

6x 6pin
9x 6+2pin

3. Yes, the molex power will only 'extend' the PCIe slot power, and the GPUs will require their PCIe connectors populated.
 

You do not plug that adapter cable into the PSU's modular connector panel. You need to install the (10+18)-pin end of the cable into the PSU's modular connector panel and then plug the 24-pin ATX power connector end of the cable into one of the two adapter's input connectors.
Dual_PSUAdapter.jpg
 
Solution