My first advise would be, upgrade your PSU.
What you have is a very cheap 400Watt PSU from a not well known manufacturer (Circle) who probably isn't in assistance anymore, possibly but doubt it.
It should run the 750Ti but largely depends on what the rest of your system is pulling from the PSU, so cannot accurately advise without more information. I very much doubt it has 6pin/8pin GPU connections and would never advise using Molex/Sata to GPU adaptor cables!
You can get 2nd hand Corsair PSU's on fleabay pretty cheap these days. Look for a min of 80+ Bronze.