Re: does cause the computer to crash within the hour similar to when I had the GT 730 in there after I swapped the PSU. at this point it looks more likely this XE3 psu is defective.  Dell does not release proprietary white 6 pinout but from all evidence they used the same across multiple models.  therefore, the pinout of XE3 psu by design is identical to 5070 psu.  however, in your particular XE3 psu the PS on and PS ok pins may not be meeting spec during low duty.  It is still quite strange that during high duty this issue does not surface.  I do not have a good explanation yet.   since your purpose is to use this as a temporary gaming pc running high duty it may not be worth your time trying to figure out exactly why.  Just use it with the 3060ti.  otoh, for curiosity there is nothing you can do to fix the XE3 psu you have (generally you cannot open a psu to service).  you could ask the seller to send you a replacement XE3 psu to see if you have better luck, or try a different model.  I made a complied list of 360W Dell thin form factor psu.    
Hello.  New to the community here.  I had almost zero knowledge of upgrading hardware prior to 2 months ago, so please bear with me.  I'm more of a software/simple hardware upgrade type of guy, and am truly enjoying learning about hardware compatibility, etc.  Especially on the Dell proprietary everything...Original setup: Dell Optiplex SFF 5070 Intel I7-9700 @ 3.00 GHz 16 MB ram 500 GB SSD HD NVIDIA GT 730 200W 5070 SFF PSU I can provide service tag, but not sure if that's recommended on the forum. Our 8 year old son is getting away from Xbox and into computer gaming, especially with a VR headset and/or 3D gaming.  My GT 730 was a joke for that...  My goal was to convert my current AutoCAD SFF workstation that I use for work to the best gaming computer that I could to hold him over until we purchase him a true gaming computer next year after he gets his feet wet.  I was able to purchase a new 12GB RTX 3060, so I jumped on it assuming I could just swap it out like the old days (which I can bill to my company).  Nope...  Required more powerful PSU and external PCIE adapter as well as it's not a low profile card.  So, I purchased a L360EGM-00 360W SFF w/6 pin PCIE.  It provides an additional 6 pin PCIE connector for my GPU and looks exactly like my current SFF PSU for the P1 and P2 connectors.  Same wire colors, size... Everything. I also purchased a PCIE stack with GPU relocator mount so I can install the GPU externally.  I will cut a bit of the side PC box cover panel out, cover the edges with rubber protectors, and enjoy the lower temps. I assumed that having the same 4 pin P1 connector and 6 pin P2 connector would work happily with my setup.  Why would it not???  Game on!  Again, nope.  Apparently that's intended for the XE3 system.  OK, now I'm lost with my issues as described below.  Right now I'm running the 3060 with the 360W PSU with the side cover off and it runs absolutely perfect in "high performance" mode.  I checked the temps and wattage consumption through HW Monitor, and the GPU actually achieves about 170 Watts as NVIDIA claims.  CPU, etc is about 80 Watts when hammered, so it should max out around 250 Watts+ assuming no insanity.  360 W hopefully will cover it.  Here are my issues: 1. The computer no longer has the jet plane fan whoosh at boot like it used to.  Dead silent at boot. I verified that all fans work, but jut seem at idle.  This is the same with the original hardware listed above (GT 730).  The seller of the PSU plugged it into an older compatible system to mine, and verified that the fans don't spool upon boot.  They spooled properly when connected to an XE3 system.  The system completely turns off 20% of the time when I reboot.  Again, zero fan whoosh sound since I replaced the PSU.  That seems to be part of the issue in my opinion.  I noticed that when I change the power settings to "high performance" it wont crash no matter the load when running (100% for HOURS),  "balanced" crashes periodically with simply surfing the web.  Almost like the PSU is shutting down since it's not seeing enough voltage at startup.  Odd... 2. The computer would simply die at around 5 minutes with the original GPU after I installed the 360W PSU.  Always under minimal load.  It never shuts down under full load, especially with the RTX 3060.  Can run for days at high load. 3. I noticed the below PSU for the XE2 system.  It's most likely more compatible with mine, but at a 45 watt reduction.  I never heard of this until recently.  Would probably solve my issues, but at a lower threshold for power consumption.    4FCWX 04FCWX 315W For Dell Optiplex XE2 SFF Power Supply D315ES-00 Please let me know your thoughts.  To me, what I'm attempting is a viable option for the SFF as a gaming platform.  At least temporarily... I've ordered, and plan on upgrading the CPU heat sink and fan based off the recommendations below.  The wire converter matches perfectly from Noctua to Dell fan pins.  It even seems to sort the original J9G15 fans.  Fantastic information...  Thank you [NAME]   [URL] I'm just looking for a possible workaround using my current 360W PSU.  I'd downgrade to the 315W if there's no other option.  It just seems like there's a voltage warning/shutdown on the PSU that I can comply with by adding additional consumption or voltage consumption to the motherboard.  I plan on adding two 12V fans run off the SATA ports to be full speed all the time, so maybe that will close the loop.  But again, it just doesn't like the boot up... Much appreciated!  
Dell 5070 Optiplex SFF PSU and GPU upgrade