Ah, you have the SFF model. It's the 8000 Minitower models that came with the 320w--which has the same proprietary plugs instead of the 24-pin, but won't fit in your case.
Well I think the GT1030 is an excellent card but people seem to have problems getting its Hybrid vBIOS to boot in many OEM systems (almost always works in aftermarket Core 2 motherboards) so I would suggest buying from someplace that takes returns. The MSI 750Ti cards had a vBIOS switch to force Legacy BIOS mode so worked no matter what. And unfortunately the competing AMD RX540 is only described as <50w.
FWIW, back in the day I ran a 110w HD4850 for years on a C2Q with just a 240w PSU so many things you don't expect could work do. It even only had a...