GTX 750 = 55 W.
The answer to that is: maybe. We'd need to see the full specs of the PSU - if you can post an image somewhere and link to it here of the power distribution specs label of your PSU, we might be able to answer it.
I have a Dell Inspiron 3647 small desktop. It has a 220W PSU, but offers 18A on the 12V rail, thus 216W on the 12V rail. So almost all the available power was offered on the 12V rail.
I ran that with a Haswell Pentium (54W CPU) and a Radeon R7 250E (55W) GPU. Never had a problem.