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.
65 Comments on NVIDIA GeForce RTX 5090 Runs on 3x8-Pin PCI Power Adapter, RTX 5080 Not Booting on 2x8-Pin Configuration
The only hardware that doesn't have needs is the one sitting on your shelf.
in the direct current world is wattage equal voltage multiplied with current or current multiplied with current multiplied with resistance or voltage multiplied with voltage divided by resistance. Basics.
(Blame this forum for not proper software to make mathematical basic formulas from 3rd school year here.)
Auswolf stated - the card will not boot without all proper connectors during bootup.
You need to bootup the hardware first.
than you can make software hacks and tweaks
when the hardware does not bootup with less connectors, you can not undervolt
i hope this is clear now.
Remember:
Like in OSI layered modell. (that is very important you may read it and learn it please)
Physical layer = hardware first - missing connector - nope
much later comes software
much later comes the application
edit: don*t be angry. These are basics in electronics or physics or mathematics. The other stuff are basics from my education. nothing new.
edit: That is not an argument get another power supply unit. When the card takes less Watts an older power supply could be more the fit. The real reason are those power spikes which are insane. Which most likely previous cards did not really generate. See igorslab. Sometimes he is right, sometimes there is room for improvement. Why should someone needs a new power supply unit when the older card had similar wattage as the newer card? the only reason are those power spikes.
The connector can distinguish between 4 different wattage modes for the 600 Watt connector. The card should bootup.
Check post #22 link - the card should even bootup with 100 Watts - initial permitted power at system power up. The card should run fine with 150 Watts. Any questions?
Assuming htat spec is correct in #22 - nvidia has a design error with that particular graphic card mainboard - or software error with that particular graphic card mainboardWhen you reply, please provide datasheet for all components involved, especially for the controller ics, provide full schematics for a recent powersupply unit, atx 3.1 spec and full schematics for those cables and adapters.I doubt the Wattage is limited over the PEG slot. I forgot which card it was, i think one card even took over 125 Watts over the PEG slot.
Anyway. Nvidia does not contribute to open source software - see recent gamers nexus video.
I invite AMD, Nvidia, INTEL, power supply companies and the others: Please publish the full specifications, the full schematics, the full datasheets, the full register and programming sheets for all components being used on pc parts.
Well it's easy to sell garbage, when you do not publish the full specifications and no one can check if the firmware, software, hardware is working according to the specifications. Check e.g. the linux kernel (it is only the kernel!) for all the workaround for the hardware and firmware bugs. A generic statement.
I really want to see in less than 2 minutes the full nvidia graphic card connector specs on the nvidia homepage in english. That includes datasheet, application notes and other common documents needed to design a device.
I only know gamers nexus measures with internal checked and before external calibrated measurement device the peg slot and all the cables.
I doubt 12 Watts on the peg slot are 2 watts. I doubt the windows software reads out these values correctly.
source:
NVIDIA GeForce RTX 5090 Founders Edition Review & Benchmarks: Gaming, Thermals, & Power
That measurement is plausible.
I also wrote on those cpu tests in teh past. I want to see the wattage for every cpu pin - not the hole mainboard nonsense. Like igorslab does for example in the past. Igor for example can not differentiate between cpu only consumption and the correct cpu + mainboard + mainboard peripherals + ram consumption + something else which may be on the mainboard I forgot as of now.
developer.nvidia.com/open-source
github.com/NVIDIA
Let's reflect a little bit on us talking about how a card should behave 'power wise' when its one of the rare cards that has odd behaviour and a... oh! 600W power allowance! Gosh
I had a Nvidia 9800m gts (asus g70sg) with "bar" error in the firmware. I patched by hand every kernel source I used with that graphic cards for years. It was several years, not only weeks or months because the card had a hardware - firmware error with the binary nvidia-drivers.
I had a nvidia 660m GTX (asus g75VW) - barely any open source stuff
I had in 2023 to test again the windows 10 pro and the gnu linux driver state again a second hand MSI 960 GTX 4GB card. I used it for several months to test it. One of the reasons why i had before radeon 6600XT and bought after that radeon 6800 non xt and later radeon 7800XT. I'm one of the few users who did not test intel, but reevaluated the other gpu manufacturer also for driver quality, daily windows 10 pro and the linux user space daily scenario. I was also interested about the 4GB VRAM and how slow that card really is.
Just do not tell stories who none believes. I used notebooks with nvidia graphics with the same gnu linux installation for a very long time.
Years ago I checked this page - no progress - not the bare minimum works
nouveau.freedesktop.org/FeatureMatrix.html