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800w PSU not powering 2 gpu?

Akli

Hi, ive been running this pc no issue. Until i connected a second gpu, when i start it  everything turns on (the fans of both rotate), but none of them send a signal to the monitor. 

All of the tried GPU work fine if they are alone, the issue is when more than one are at the same time, and just to make sure  i have the drivers for all of them installed.

 

The PSU is a Corsair PS800 ive used for years, and a 800w PSU should be well above what this system requires.

 

- Could it be that the issue or another thing? 

 

 

PSU: Corsair PS800

Motherboard: B350F

CPU Ryzen 7 1700x

Usb keyboard and mouse.

Drives: 2ssd, 1usb, 1normal.

Ram: 32gb

Case fans: 4noctua 

Gpu 1: 3070

Gpu 2: tried with 980ti and rx580.

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you tried using the 2nd slot alone? or tested all 3 gpu in 1st slot?

-sigh- feeling like I'm being too negative lately

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1 minute ago, Moonzy said:

you tried using the 2nd slot alone? or tested all 3 gpu in 1st slot?

 

The 3070 remained in the slot 2, then i tried it with the rx580 in the slot 1, and then swaped the 580 with a 980ti.

Then i tried those in slot 1 while disconnecting power from the 3070 and then the monitor started fine.

And, though everything fires up inside the pc, as the monitor doesnt, im not sure if the system actually starts.

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5 minutes ago, Akli said:

The 3070 remained in the slot 2, then i tried it with the rx580 in the slot 1, and then swaped the 580 with a 980ti.

so you tried:

Slot 1: RX580/980Ti

Slot 2: 3070

 

5 minutes ago, Akli said:

Then i tried those in slot 1 while disconnecting power from the 3070 and then the monitor started fine.

Slot 1: 3070 (no power)

Slot 2: RX580/980Ti

 

is this correct?

 

and any GPU in any slot works as long as it's only 1 GPU, am i correct?

any risers? all PCIE power plugged in yes?

-sigh- feeling like I'm being too negative lately

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2 minutes ago, Moonzy said:

so you tried:

Slot 1: RX580/980Ti

Slot 2: 3070

 

Slot 1: 3070 (no power)

Slot 2: RX580/980Ti

 

is this correct?

 

and any GPU in any slot works as long as it's only 1 GPU, am i correct?

any risers? all PCIE power plugged in yes?

All correct. And not raisers yet.

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Just now, Akli said:

All correct. And not raisers yet.

Tried rx580 with 980ti?

 

Normally system would start fine, it'll just shut down if you over draw the current, won't just refuse to start up, unless startup already consumes too much current (unlikely)

-sigh- feeling like I'm being too negative lately

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What kind of SSDs are those? If both are NVMe, second would share PCIe lanes with the 2nd 16x slot from the chipset.

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3 minutes ago, Moonzy said:

Tried rx580 with 980ti?

 

Normally system would start fine, it'll just shut down if you over draw the current, won't just refuse to start up, unless startup already consumes too much current (unlikely)

I havent tried 980ti with the 580, but mainly because the 3070 is the priority, only tried with the 980 to ensure it wasnt a compatibility issue with the 580.

 

The weird thing is that the fans and all start up and stay on.

 

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2 minutes ago, Zagna said:

What kind of SSDs are those? If both are NVMe, second would share PCIe lanes with the 2nd 16x slot from the chipset.

 All pcie slots are empty, only using 2 of the 3 pci x16 with the gpus.

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2 minutes ago, Akli said:

I havent tried 980ti with the 580, but mainly because the 3070 is the priority, only tried with the 980 to ensure it wasnt a compatibility issue with the 580.

 

The weird thing is that the fans and all start up and stay on.

I have absolutely no idea than, soz

 

3 minutes ago, Zagna said:

What kind of SSDs are those? If both are NVMe, second would share PCIe lanes with the 2nd 16x slot from the chipset.

Would assume that's not the issue if each slot works individually, but yea some board do disable 2nd pcie slot if you're using certain m.2 slots

-sigh- feeling like I'm being too negative lately

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3 minutes ago, Akli said:

 All pcie slots are empty, only using 2 of the 3 pci x16 with the gpus.

Yes but what kind of SSDs? SATA or NVMe?

Nevermind, Strix B350-F has only 1 M.2 and thus this doesn't apply at all.

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2 minutes ago, Zagna said:

Yes but what kind of SSDs? SATA or NVMe?

2 satas

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The problem is the wattage ratings of PSUs are measured using resistive loads with currents at 0Hz

.

When powering a system with currents at frequencies in the Ghz, the power cables reactance reduces the power it can transfer.

 

If you want to improve power transfer, you need to reduce the reactance in the cables by making sure your PC case is properly bonded to the PSU and ensure all devices connected are chassis Grounded.

 

Have a look at this thread...

 

 

 

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