Will this graphics card work in my pc?

I just recently purchased a desktop pc from lenovo that came with a gtx 750 graphics card. My pc only has a 260w power supply but both the gtx 750 and gtx 750 ti require a 300w supply. The 750 works fine right now but I was wondering if I could switch out the 750 for the bit more powerful 750ti and be fine. They both require the same amount of power.

It's better safe than sorry in any case upgrade your psu to at least a 400 watt one, i would say yes with the 260 watt psu upgrading to a gtx 750 ti but my problem for how long will that psu will last

That 750 is OEM and was probably designed to work with that 260w
I wouldn't put anything graphics card in there until I upgraded the power supply first

I suggest upgrading the power supply first. Lenovo basically stuck in the weakest power supply they could get away with for that card; putting in a more powerful card could spell trouble.