PC fail to detect second GPU!Please Help!

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M

marckusc

Mar 14, 2018
4
0
10
What i have:

GPU = 2 X AMD Radeon RX 570 8G (Bought New)
OS = Win 10 64 bit (Upgraded a day ago from 32 bit)
PSU = installed a TX750M Corsair a day ago
Motherboard = From Dell, Precision T1600

What happened?

It will detect the 1st GPU. Upon connecting 2nd GPU (power off/on), it will hang with no dell logo, no win logo. Nothing happens. Both GPUs looks powered. No output to display unit.

What i have done:

1) Tested GPU Singly. Works & boots up. (GPU not likely a problem)
2) Tested each PCIe riser with 1 GPU singly. works.(PCIe Riser not likely a problem)
3) Tested 4 PCIe slots. Works singly. Add second GPU (no output no screen). One slot is probably shorted (Never use before).
4) Tried using one GPU and one existing Graphics card (Nvidia Quadro 600) Works. Outputs to 2 monitors.
5) Updated BIOs from Dell. No advance settings available. No access to UEFI.

Any help appreciated. Thank you.
 
Solution
W
Look at the 5V. and 3.3V rails on the old PSU. Dell may be powering the 2x GPU slots from the 3.3V. PSU rail. You may see something like 20-22A there due to this. The aftermarket PSU may have enough 12V. but not enough 3.3-5V. for that configuration. My EVGA B2 850 has 24A there.
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Wolfshadw

Wolfshadw

Titan
Moderator
Aug 3, 2006
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While there's no harm in doubling the recommended watts for a power supply to ensure adequate power for a dual card system, it's certainly not necessary.

Given the link The Paladin provided, Typical Board Power is only 150 watts. However, given that it has both a PCIE 6-pin (up to 75 watts) as well as a PCIE 8-pin (upto 150 watts) connector, The max one card could use would be 300 watts (including the 75 watts from the PCI-Ex16 slot). So if the recommended power supply for one card is 450 watts, then I'd be looking for a 750 watt to 850 watt power supply for running two.

Of course, I'd also make sure that the power supply came with the proper cables for running two separate graphic cards.

-Wolf sends
 
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W

william p

Splendid
Sep 22, 2010
3,788
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30,340
Did you try asking AMD about Crossfire drivers? FWIW Microsoft dropped built in dual GPU support in DX12. Individual games must support it or it doesn't work. DX11 has the support built in.Workstations are designed to use dual GPUs, but not in SLI/ X-Fire mode. Right now it's doing what it was designed to do.
I hope you find a solution as I own a couple Dell workstations and want to X-Fire some old HD6990/6970s for Trifire to avoid micro stutter. Or pair up some R9-285s I have. Crypto miners are nuts about high RAM GPUs, maybe just sell out get one high end card and be done with it. Miners like lots of GPUs, and lots of VRAM.
 
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M

marckusc

Mar 14, 2018
4
0
10
the PSU i have was a newly purchased Corsair 750W unit. The mobo i have does not support x fire. until now i can only attach a RX570 8g GPU and a Quadro 600. The moment i try to install 2 RX 570, system will not start. no beep no bootup.. but both GPU fans spinning. CPU fans also spinning.
 
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W

william p

Splendid
Sep 22, 2010
3,788
100
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Look at the 5V. and 3.3V rails on the old PSU. Dell may be powering the 2x GPU slots from the 3.3V. PSU rail. You may see something like 20-22A there due to this. The aftermarket PSU may have enough 12V. but not enough 3.3-5V. for that configuration. My EVGA B2 850 has 24A there.
 
Upvote 1 Downvote
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