I have an alienware x51 r2 and I am upgrading my gfx card to an evga gtx 960, which will require more watts, and I have a 650 watt psu that i am having trouble installing. As of now im not worried about the size and the fact it is an internal power supply, I will be getting a new case later. if anyone could walk me thru it tho or link me to where i can find out how to install my new psu i'd apprecite it.
x51 comes with either a 240 watt or 330 watt...if you have the 240 watt I don't think a 960 will work. But the 330 watt will run the 960 and 970. Some even claim success with a GTX 980 on the 330 watt power supply.
It's enough. If it wasn't, Alienware wouldn't be supplying GTX 960s to X51 R2 and R3s.
I also speak for personal experience that a GTX 960 does work with a 330w PSU and i7 regular processor (not the extreme processors like i7-5820k). I've even used an R9 285, a GPU with a higher TPD, with the X51 and it worked without problems.
Currently owned computers:
AW13 R2 | i7-6500U | GTX 960m 4 GB + GA (R9 285 2 GB / RX 480 8 GB) | 16 GB 1600 MHz | 1800p Touchscreen | 2 x 500 GB SATA M.2 | Graphics Amplifier Performance Analysis with 13 R1
Desktop | i7-3770 | GTX 980 4 GB | 16 GB 1600 MHz | 120 GB mSATA + 960 GB SSD + 2 TB HDD | 600w PSU
Formerly owned computers:
HP Pavilion 15-n280us (given away) | Apple Mac Mini 2012 (sold) | m15x (damaged mobo) | 13 R1 (death by unknown) | m14xR2 (Tradied In)