PSU requirements for HD2 TDM System

[oldlouisvillerecords]

I have Pro Tools 8 HD running on a HD2 TDM system with a Digidesign 192 8x16x8. My PC specs are Dell Optiplex 9020 MT, Windows 7, i7-4790, 2 SSD (1 for os + 1 for storage), 16gb Ram, Dell Geforce GTX 645, Digidesign HD accel core card pcie, and Digidesign HD accel card pcie. It is also likely that at some point I will upgrade the cpu to the i7-4790k.

The weak link in this setup is a Dell OEM 290w psu. Therefore I'm looking to upgrade the psu, but the Dell Optiplex 9020 motherboard has a propriety 8-pin connector, so an aftermarket psu is problematic.

The first option I have is a Dell OEM 365w psu that can be swapped into the pc seamlessly. Unfortunately this is the highest wattage I can go OEM.

Will a 365w psu be enough to power this system?

The second option I have is to use an aftermarket psu with a 24pin to 8pin atx adapter. Not going to lie the adapter sketches me out after reading about it possibly frying the motherboard in reviews online.

However, if 365w will not cut it, then I am okay to use the adapter for a proper power supply. Any recommendations on how much power is necessary for running my system? Any recommendations on a particular psu that you've used for an hd rig?

Thanks.