@ tsnor
While you may be able to use adapters, the power supply still needs to have the extra power for the card. Chances are that power supply the OP has, due to its lack of cables(not even enough 4 pin molex) is likely too old to support the new card.
You know that my current 300(who would not want to run a gtx 650 to on one of those
Even that power supply has 1 6 pin pci-e cable) watt power supply has more power then an older 380 watt unit.
If the power supply is too old, I would avoid adapters and recommend all other users do. The exceptions are low tdp cards(lets say 90 and under since 75 will come from the board) and high powered power supplies from just before the release of PCI-e power connectors.
I see you listed FULL system power, but you also know that on older power(well technically all) supplies, only a percentage(A much lower amount then new ones) of the total sticker rating was on the 12 volt lines right.
For instance my old Antec Truepower 380s(single fan quiet one for the Sonata case) had 18 amps @ 12 volts. That was just 216 watts. If the cpu needs 95 and the card needs 150. I am so screwed(if they get to FULL load).
That does not include the board and whatnot. While not everything uses the 12 volt rail, the CPU and GPU do for sure.
So its not about wattage of the unit, but about how much wattage you can get on the 12 volt rail.
I hope this is usable info, I am NOT trying to put down what you say. Check out how much power power[12 volt] the EA380 has vs the old TP380s. Both are 380 watt rated units.