Weird Problem

Ok this is my first time posting on here. I am having a (to me) weird problem and not sure if it is common.

So I have just got into mining, building my first gpu rig. Started with one card and slowly expanding. I have 3 cards now, all AMD 6600 XT Mech X2. I have a 750 W PSU that I recently swapped for a 1000 W PSU because there weren’t enough ports to run off the 750 W PSU. I had tried to and was successfully able to power the cards and their risers off the 750 W PSU but realized it wasn’t very safe and an error was thrown every now and then.

With the 1000 W PSU I have one VGA port powering 2 GPUs and one port powering 2 risers for them. No problems at all. I connected my third GPU to another VGA port and it’s riser to yet another. The thrid card consistently seems to cause a reboot every 30 seconds or so.

Troubleshooting…
-disconnected the third GPU and everything works fine.
-reconnected the third GPU to a new PCI on the motherboard and get the same reboot problem.
-changed the riser for the third GPU and still got the same reboot problem.
-Disconnected the second GPU so that the 1st and 3rd GPUs each had their own port on the PSU and both GPUs caused the reboot with the “GPU dead” error for GPU 0 (the first GPU)
-connected both the 1st and 2nd GPUs again and running fine.

So what I am thinking is that the PSU VGA port powering one GPU each causes problems but if a single VGA port on the PSU powers 2 GPUs there is no problem. Is this normal? Has this happened to anyone else? What could cause this?

I have a 4th GPU coming tomorrow so I will try powering the third and fourth GPUs off the one VGA port just like the 1st two.

Hi,
One cable for each Gpu with a riser… this is the correct for your cards…and always use 6 pin for risers…if you dont have enough 6 pin also u make through molex for risers…

Hey thanks for the reply. It turns out it was the cable to power the riser. One of the ends of the splitter was bad. I replaced it and all is running well.

I know powering two GPUs with one VGA cable isn’t recommended but with the 6600 XT drawing less than 100 W and the VGA able to provide 255± it works. I couldn’t find a power supply that had more than 6 VGAs/PCI-Es and didn’t want to get a server power supply. My next rig will be a 12 GPU rather than 6 so I’ll get the server power supply with breakout board. Right now with the 4 6600 XTs and 4 fans it is only pulling 375 W from the wall.

I appreciate the help!

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