If you already have the 300w psu, it is sufficient for discrete video card 1650S or 1660S.  The psu has a black 6 pin connector for 1650S which has a 6 pin socket.  For your own 1660S, you can use a Dell 6 to 8 pin adapter as retail 1660S card typically has an 8 pin socket such as this one from PNY.  [IMAGE]   Most of the power in that 6 pin powers the gpu chip in the video card.  The pciex16 slot also supplies power to the video card.  The video card fans take up minimal power only. 
I am awaiting contact with Dell Support, but thought I might gain a more in-depth answer, certainly a variety of thoughts at least if I posed the inquiry to the community.I purchased a new Inspiron 3910 in December 2022 and at the time I had a different intended use for it that has since changed.  The unit I purchased had the i7-12700 with integrated graphics.  Frankly, even with the intended use change, the integrated graphics will likely be adequate 75% of the time, but the change means that the remaining 25% of the use will need a discrete GPU of sufficient capability that only a discrete GPU will make the use complete in reasonable time.  The Inspiron 3910 is available with just integrated graphics, or with the NVIDIA GeForce GT 730 OR GeForce GTX 1650 Super OR GeForce GTX 1660 Super.  If I upgrade, the change from integrated to the GT 730 is not sufficient to make the attempt.  I have found the GeForce 1650 Super and 1660 Super for reasonable prices.  The power supply in the i7 is a 300W which is the same wattage as in the units with discrete GPU's from the factory.  I have an available PCIe x16 slot.  My system has 32GB of RAM in dual channel mode, 2 SSD's, optical drive, really everything is great, but one item that will be problematic if I don't find a resolution.  In the models that came with discrete cards from the Dell factory, the card occupies the x16 slot, but has a 6-pin power connection which I believe powers the two fans on the specified discrete GPU cards.  What I don't know is if I purchase a 1650 or 1660, is if I will be able to interface it with the power supply using a cable connection.  What, in the community's opinion, would I need to make such a connection?  I am sorry for being so verbose, but I wanted to be clear the simplicity of the problem, yet it is a no-go if I can't interface it.  What info, opinions, insight, etc. would some experts have to offer?  Can I make the upgrade?  Essentially, if the upgrade is possible, what parts might I need?  Is there a part or a part name that I can find on Amazon, CDW, Dell, etc?  What, in addition to the card, would I need as the final part in the upgrade?I can't thank the community enough in advance!  THANK YOU!
Adding Discrete GPU (GTX 1650 Super or 1660 Super) to Inspiron 3910