If the 300w psu (24/4 pin) is small form factor, then it may fit the 755 SFF case and work.  Dimensions of stock psu is 6 cm x 21 cm x 8 cm. A standard form factor 24/4 pin ATX psu would have to sit outside 755SFF case while connected to motherboard. Dimensions of an ATX power supply are 150 mm width, 86 mm height, and typically 140 mm depth, although the depth can vary from brand to brand.
I wanna know if a Dell Optiplex 755 can run a 300W PSU because i have a Dell Optiplex 755 sitting around, with the original psu dead. I tried to use a "working" psu but it turns out it was faulty and it cut the power sometimes. So I wanna get a new 300W PSU and I still wonder if it's gonna work or not because I don't wanna blow my Dell Optiplex 755 up.
Can the Dell Optiplex 755 SFF run a 300W PSU