Re:  I saw RM550x is 8-pin but dell's motherboard use 6-pin PSU, how can I solve it? dell motherboard uses proprietary white 6 pin + white 4 pin.  Standard ATX psu 8 pin is EPS for cpu.  They have completely different pinout. To power rtx3060/2060 you have option to upgrade to Dell 360w psu which can sit inside the case.  or you can install a 24 pin ATX psu outside the case with adapter. 3471 is small form factor with 92.6 mm width, and Dell stock psu is thin form factor with 65 mm width, so if you use a non-Dell standard ATX psu such as RM 550X, it has to sit outside the case, because it would not fit inside.  To use ATX psu you must get a 24 to 6 pin adapter for Dell motherboard.  Verified working one is from Amazon.  This converts standard psu 24 pin to Dell proprietary 6 pin for the motherboard.[URL] Re: Samsung 980 pro PCIe gen 4 nvme ssd 3471 spec mentions on board M.2 is for sata only.   M.2 2230/2280 solid-state drive SATA AHCI, up to 6 Gbps Up to 512 GB in order to support nvme ssd you need to use a low profile pciex4 ssd adapter and install in PCIe x16 slot.  The other slot on motherboard is PCIe x1. [IMAGE]  
Now I want to add a graphic card (rtx2060 or 3060), a M.2 SSD (Samsung 980 Pro 1TB, got as a gift) into my Inspiron 3471 as upgrades. Therefore I have to change the PSU and I plan to use RM550x or RM650x.   What I want is to keep the whole motherboard & HDD (since i5 9400 is not that bad and I don't want to spend that much to build a whole new PC), I can afford to buy a new case for better airflow. However I saw RM550x is 8-pin but dell's motherboard use 6-pin PSU, how can I solve it? Also can Inspiron 3471 support Samsung 980 Pro? (Not in terms of full speed since I know Inspiron 3471 does not support PCIe4.0, I am already happy enough if I can use the SSD)
Inspiron 3471: Adding Graphic Card & M.2 SSD, change PSU