I have a hp 3500 mt and an intel 3240 and i was wondering if a 300 watt would be good for a 750 ti and if not can you recommend some that would be great for a 300 watt that does not require external power
The GeForce GTX 750 Ti graphics card comes loaded with next-gen NVIDIA gaming technology like TXAA, FXAA, GPU Boost 2.0, and GeForce Experience, as well as 128 more NVIDIA CUDA cores than the GTX 750. Check it out.
So if it's a good psu with quality. That wattage should be well min required.
Other that the 750ti, there are two better ones I could recommend that will be generally better. The GTX 1050 and 1050ti are both good GPUs, and both do not require any external PSU connections at all.