Gigabyte RTX 5090 modded to support two 12V-2×6 power connectors
Although we talk a lot about 12V-2×6 power connectors in terms of their issues with thermals and often melting, some users aren’t as concerned about such issues. In fact, they would rather add even more power if they could. Technically this is possible in two ways: through shunt modding, which tricks the card into believing it draws less power than it really does and raises the overclocking limit a bit, or by using dual power connector cards, which do exist but are very limited and mainly serve as vehicles for extreme overclocking.
In this case the modder also performed a shunt mod on the RTX 5090. The original 2 mΩ sense resistors were replaced with parts around 1.2 mΩ, which means the card underreports power draw by a factor of roughly 1.67. Power monitoring tools still show values based on the old resistance, but the real board power is around two thirds higher. This is why readings such as 485 W from the BIOS translate to more than 800W of actual GPU powe r once the shunt factor is applied.
Worth reminding that on the market we only have one card that features two power connectors, the special version of the GALAX RTX 5090D HOF . The soon-to-be-released ASUS RTX 5090 ROG MATRIX will also have two connectors, but the second connector uses GC-HPWR. However, technically the first card has a max TGP of 2000W (just a software limit) and the latter is said to boost up to 800 W.
Room for two 16-pin power connectors on Gigabyte Gaming OC, Source: TechPowerUP
Meanwhile, one user decided to try something else by combining both ideas and making their very special Gigabyte RTX 5090 AORUS Stealth card. This was only possible because the Gigabyte card has a board that is reused by different models (AORUS/Gigabyte series). One power connector placement serves the standard models, while the secondary position is for the AORUS Stealth model, using a special hidden power connector design.
Modder “Yogimuru” decided to check if both connectors can be used at the same time and, long story short, it apparently works. This confirms that the power connector is not isolated and they exist within the same 12V power plane. Should something go wrong with the first connector, a GPU repair service could technically move the connector elsewhere if that was necessary.
There was only one issue with this idea: the non standard power connector placement does not fit the original cooler, so the modder had to improvise by adopting water cooling . It is safe to assume that the warranty on this card is long gone.
Source: Yogimuru
Unfortunately, Yogimuru has no equipment to test if both cables provide the same power, but he used a thermal camera and confirmed that both connectors get equally hot. The card’s BIOS reports 485W of power being used, but since this involves shunt modding the actual power use is 808W. This is confirmed by power supply power reaching 975W with other components included.
Benchmark results show that the gains from this setup are smaller than the power numbers suggest. GPU frequency can reach around 3.2 GHz and scores land near the top for this hardware configuration, but the improvement over strong air cooled or stock water cooled results is minor. GPU temperature still climbs to about 67C because of a less than ideal water block fit, so thermals rather than power limits appear to cap performance.
Well, at least we know such mods are possible.
Source via Uniko’s Hardware :
