4090 and 12VHPWR voltage question
The replies to this topic are baffling to me. Either I'm completely misunderstanding the question, or everybody else is.
Could lower voltages cause the connector to melt?
Yes*. Power (W) = Voltage (V) * Current (I). With a constant power load if you decrease the voltage the current will increase. High current is what can cause cables to overheat.
Would a voltage of 11.843V on the 12V rail cause the 12VHPWR connector to melt?
It shouldn't. 11.843V is still within spec. With a 4090 at 450W power draw the current would increase from 37.5A at nominal voltage (12V) to 38A at 11.843V. An extra 0.5A on the connector shouldn't be an issue. The 12VHPWR connector is rated for 9.5A per pin, there's 6 12V pins for a total maximum current rating of 57A. (Note: The graphics card draws up to 75W from the PCIe slot, so in practice it would only be drawing 375-400W from the 12VHPWR cable - but people overclock and increase the power limit so 450W from the 12VHPWR cable isn't totally unexpected)
IIRC the melting of 12VHPWR cables was mostly attributed to poor contact between the connectors/poor contact between individual terminals.
With all that said. You can't trust software readings for voltage measurements.
The software reading you are looking at "GPU Rail Powers" is not even a voltage reading. It's just displaying data aggregated from various sensors. The minimum "GPU Rail Voltage" is the minimum voltage from any of the 12V voltage sensors. The maximum "GPU Rail Voltage" is the maximum voltage from any of the 12V sensors. GPU Rail Voltage is not an actual reading from any sensor. That's probably why there's a large swing between the minimum and maximum values. Depending on what the sensor is monitoring and where it's on the board, and just in general how accurate that sensor is, one sensor might be normal at 11.9V while another sensor might be normal at 12.2V. But when you look at the min/max across all sensors you see 11.9V and 12.2V and think that's a huge change.
If you click the > to expand the GPU Rail Voltage in HWinfo64 it will show you the various sensors and their values.
You can see in the image below taken from my HWinfo64 it shows the minimum voltage of 11.864V which is the minimum voltage recorded on the PCIe slot input sensor and the maximum voltage is the maximum voltage read from the GPU 8pin #2 voltage sensor. The difference between the minimum and maximum on each individual sensor is actually much smaller.
On 1/14/2025 at 10:17 AM, t40r said:So the reason I wrote all of this out, is to ask. Is this acceptable and normal for the card? Is it something that may be starting to have a problem after using the pc for a couple years now? Should I upgrade the PSU? To my knowledge it's actually one of the better ones with full Japanese parts etc which is why I went with it.
Your power supply is fine, and it is a good quality power supply.
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