2012 Mac Pro (GTX980Ti) [1st,12C,E] + GTX 780 Ti x3 @ 64Gbps-PCIe (Cyclone Backp...
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2012 Mac Pro (GTX980Ti) [1st,12C,E] + GTX 780 Ti x3 @ 64Gbps-PCIe (Cyclone Backplane) + macOS 10.11.6 [hoeveler]  

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Merritt Bishop
Active Member
Joined: 6 months ago

@hoeveler, Interesting, I wonder if you just had bad luck or if you were pulling too much out of the PCIe slots and there was not a proper limit set/negotiated. PCIe slot power limits are definitely a thing, as I found in my project I was getting major throttling due to them until I hooked up external power to the slot through an adapter. I found PCIe slot power was limited to around 25w in my case for example. I wonder if your board somehow allowed it to pull too much and it popped something? I'd think for a backplane of that quality that would have been addressed properly though.


2018 Lenovo ThinkCentre M720q Tiny [8th,6C,T] + GTX 1650 Super @ 32Gbps-PCIe (Extender) + Win10 [build link]  

Eminent Member
Joined: 4 years ago

I think it was physical/mechanical. The PC board isn't built like modern motherboards for flex-reducing / metal fortification along the PCIe slot to reduce flexing from these massive/heavy modern GPUs. I had it stacked and though it was mounted in an open-air case, there was a little bit of flex, and I think the PC circuit board developed a micro-crack. It would click in and out of connection if the GPU was gently wiggled. So it's not due to the power limits but a self-protection circuitry I think.

2012 Mac Pro (GTX980Ti) [1st,12C,E] + GTX 780 Ti x3 @ 64Gbps-PCIe (Cyclone Backplane) + macOS 10.11.6 [build link]  

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