Monday, February 3rd 2025
NVIDIA GeForce RTX 5090 Runs on 3x8-Pin PCI Power Adapter, RTX 5080 Not Booting on 2x8-Pin Configuration
NVIDIA's flagship GeForce RTX 5090 demonstrated flexibility in power compatibility, while its sibling, the RTX 5080, struggled with stricter requirements. Recent tests by a German tech outlet, ComputerBase, reveal that the RTX 5090 can operate with three 8-pin PCI power connectors instead of the recommended four, albeit with a performance trade-off. However, the RTX 5080 fails to boot when using only two 8-pin connectors. The RTX 5090, with a default TDP of 575 W, officially requires a 600 W 12V-2×6 connector or an adapter with four 8-pin PCI cables. However, tests on the ASUS ROG RTX 5090 Astral and Zotac RTX 5090 Solid show the GPU boots even with three 8-pin cables, capping its TDP at 450 W—matching the three connectors' 150 W-per-cable spec. Performance losses are modest: benchmarks indicate a 5% drop in average FPS at 450 W compared to full power.
In contrast, the RTX 5080's 360 W TDP proves less forgiving. Attempts to run the Founders Edition and Zotac RTX 5080 AMP Extreme Infinity with two 8-pin connectors (300 W total) resulted in failure: the screen remained blank, and the card refused to initialize. NVIDIA's firmware appears to lack a lower power-limit threshold for the RTX 5080, unlike the 5090, which automatically adjusts when detecting insufficient power delivery. This requirement forces users to adhere strictly to the three 8-pin or 12V-2×6 power connectors. While the RTX 5090 offers flexibility for users upgrading from older systems, the RTX 5080's limitations may frustrate owners of less powerful PSUs. For the RTX 5090, the 5% performance penalty at 450 W may be a reasonable trade-off for avoiding costly PSU upgrades, but RTX 5080 users have no such recourse. Verifying power supply compatibility, as underpowered setups risk instability or hardware damage, is a must, and when your $2000+ GPU runs, you should at least power it properly. This experiment is more a "for science" type of run.
Sources:
ComputerBase, via VideoCardz
In contrast, the RTX 5080's 360 W TDP proves less forgiving. Attempts to run the Founders Edition and Zotac RTX 5080 AMP Extreme Infinity with two 8-pin connectors (300 W total) resulted in failure: the screen remained blank, and the card refused to initialize. NVIDIA's firmware appears to lack a lower power-limit threshold for the RTX 5080, unlike the 5090, which automatically adjusts when detecting insufficient power delivery. This requirement forces users to adhere strictly to the three 8-pin or 12V-2×6 power connectors. While the RTX 5090 offers flexibility for users upgrading from older systems, the RTX 5080's limitations may frustrate owners of less powerful PSUs. For the RTX 5090, the 5% performance penalty at 450 W may be a reasonable trade-off for avoiding costly PSU upgrades, but RTX 5080 users have no such recourse. Verifying power supply compatibility, as underpowered setups risk instability or hardware damage, is a must, and when your $2000+ GPU runs, you should at least power it properly. This experiment is more a "for science" type of run.
44 Comments on NVIDIA GeForce RTX 5090 Runs on 3x8-Pin PCI Power Adapter, RTX 5080 Not Booting on 2x8-Pin Configuration
Could also be a bad adapter, bad PSU cable connector, cable, or PSU.
To be honest, I really hate the standard. 8 pin PCIe was far better behaved than this nonsense.
I already run a GPU with 3x8pin and I wasnt ever considering to run it any differently even if it could.
I wouldn't expect a card with 2x8-pin to work with only one connected for example, even if a power target was set needing less than 225w.
You might not like it (yeah I know, Linux), but it doesn't mean you can arbitrarily decide it's invalid because it doesn't work from boot.
Undervolting also generally only affects the hardware when a 3D load - ie software, is being placed on it, even if it was baked into hardware it wouldn't matter from boot.
Just connect the card the way the manufacturer says then do what you like with it.
Edit: "But you can undervolt it" is an argument I usually get when I speak up against modern GPUs consuming enormous amounts of power. The example shows that it's not a good argument.
Then you can do what you like, run stock, undervolt, overclock, etc. I don't see any connection between a card being properly connected to the PC and then how you choose to run it.
GPU's consuming more power than before is true, and "but you can just undervolt them" I think is not a good counter to that either, but I see zero correlation to connecting it properly. You need a PSU that can handle the card in it's default TDP, typically in outright wattage with perhaps a bit of wiggle room depending how you intend to run it, but 100% required in terms of the physical connectors present. To plan to do otherwise, even if fully intending to drastically undervolt would be foolish at best.Don't quote me but I believe it's been tested and perhaps even confirmed by NVidia the 4090 essentially little power from the pci-e slot (and not circa 70-75w), shouldn't be hard to find articles on, I'll take a look. If it is the case, it'd stand to reason other 40 and perhaps now 50 series cards operate the same.
Also, I've currently got 2x 8-pin cables connected to my PSU (no pigtails in here), and I'd like to keep it that way because it's a bit hard to access without taking it out. :laugh:Agreed.
As for the PSU, 750W with 2x8 Pin should be plenty, corsair also make a native 2x8pin to 12v2x6 for their PSU's, so I should be alright with either a 9070XT or 5070Ti/5080 as long as I can fit the bastard in!
I used to be on mini-ITX myself, but had enough of the awkward cable management and lack of choice in motherboards. I wouldn't go any bigger than m-ATX, though.I've got 750 W, too, and that's exactly my plan. Then, as much as it hurts, I'm gonna put my upgrade urges to rest for a good 3-ish generations. I just wish those cards had come out before Kingdom Come Deliverance 2. Oh well. :ohwell:
BTW I am pretty comfortable with 350+W GPU power consumption since my AIB R9 390X OC version...
It is nothing to do with card configuration, what it actually draws, UV, OC etc.
I can see 10.5GB a second needing 8 watts to move data off the motherboard and into the card.