Will gtx 750 ti support ECS G41T-M16?

I would upgrade the PSU to at least a 600W PSU for peace of mind.

EDIT:
When I upgrade, I think of future builds. The 600W PSU will come in handy if and when you want to upgrade the MB, CPU and etc.
 
I agree with the advice above. A 600W brand name power supply will be better than your generic power supply. Try one of these brands : Antec, Corsair, Seasonic, XFX.
 




My current gpu(9400 gt) requires 50 watts and 750 ti needs only 20 more watts(70). My cuurent psu has 450 watts.

So as don't need any 6 pin connector can't my current psu handle the 20 watts more pressure or the 750 ti .

Another thing to mention that i will not use DVD-RAM drive.
 
If what RastilavB says is true, "the 750ti requires 20amps" and your current PSU only puts out a max of 22amps on the 12V line, you will be taking a chance there. May blow the PSU and/or the GPU too. 2amps does not leave much room for anything else.
 
You can run it but it's your risk. I will now link some recommended power supplies from reputable brands that should fit your needs :

XFX 550 Watt power supply http://www.newegg.com/Product/Product.aspx?Item=N82E16817207013&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=

Corsair 600 Watt power supply http://www.newegg.com/Product/Product.aspx?Item=N82E16817139028&cm_re=Corsair_600-_-17-139-028-_-Product

Seasonic 620 Watt power supply http://www.newegg.com/Product/Product.aspx?Item=N82E16817151096&cm_re=Seasonic-_-17-151-096-_-Product

They all have over 40 Amps on the 12V rail and their OEM is Seasonic which is one of the best power supply manufacturers. You should choose one of these.