There's going to be lots of CPU bottleneck with that processor. Might want to save yourself some money and drop back to a [strike]GTX 1060 or[/strike] 1050 Ti. That's about the performance you'll end up with anyway.
Edit: Actually, even the GTX 1060 will be bottlenecked by the i3-540.
It should. I have had several older Dells and none of them balked at newer cards. My Precision T3500 has had every card I own in it at one time or another, including my GTX 1070. What CPU is in your T1500?
There's going to be lots of CPU bottleneck with that processor. Might want to save yourself some money and drop back to a [strike]GTX 1060 or[/strike] 1050 Ti. That's about the performance you'll end up with anyway.
Edit: Actually, even the GTX 1060 will be bottlenecked by the i3-540.
1. For any card, easiest way to address the does it fit issue id to to take a tape measure and measure if the space is bigger than the card. If ya have more than 11-3/4", you good. All quoted data from newegg sales / specs page for the 1070 Strix u.o.n
Thermal and Power Specs:
94 = Maximum GPU Temperature (in C)
150 W = Graphics Card Power (W)
500 W = Recommended System Power (W)4
8-Pin = Supplementary Power Connectors