I have used Antec HCG 620W and 650W power supplies in many Dells without issue.
The cost of them was between $99 and $130 and they are QUITE heavy.
Fake Invalid parts would work for a VERY VERY Short time then overheat and Die.
The more times you try to use a non EPS 12v 2.94 Compliant power
supply the more times you risk catastrophic
failure of ALL COMPONENTS including but not limited to your RAM,
Video, Motherboard, Processor, Hard drive, Optical Drive etc.
You did not say how much this Gem Cost you but I suspect its $39 or less.
The Physical Weight of the supply and the Cost can often tell.
Scammers have been putting lead sheets in the bottom of new fakes to
make them heavier as some consumers now recognize a problem BEFORE buying it.