The Optiplex 380 was low end office computer. The MT (Mini Tower) came witha a 265W PSU. Upgrading to the Opti MT 305W is recommended. or even the Precision T3400 375W psu with a 6 pin GPU cable.
Dell uses multiple rail PSUs. The 305, and 375 both have 2-18A. 12V. rails. Any load over 215W on either rail will shut it down safely. So the 305/375 are acyually capable of making over 400W.
The 380 can support LGA775 Cpus up to Q9650.
8GB DDR3 RAM. It must Be X64 Ram (Crucial was good about supplying this) It reuns at 1066 speed.
The Zotac GTX1050 Mini drops right into the BTX computer. No GPU cable required. A 32 bit OS is helpful with an 8GB RAM limit and 4GB GPU.
Mods for this-
They only came with 2 core CPU/4GB. A 4 core heatsink and shroud from another Opti willl be needed MT 780 ia good one.
Tapemod E7500 to 3.73GHz will give the best single thread performance.
With a modded BIOS a taped X5470 Xeon has worked in these. Deosn't work in other OPTIs. 3.3GHz.
MSI OCX single fan GTX1050 3GB can have the i/o bracket cut to fit. The 375W PSU runs it, 64 bit OS is OK with 3GB GPU.