Hi, I'm waiting for the new games going to be release in 2016, so I assume new GPU better than the 960 will be needed for high graphic quality. I thought about going for a GTX 1070 since it seem to be in a reasonable price range AND it works magnificently for many. But I'm still in doubt if my Alienware desktop can handle the power supply needed for a GTX 1070 since I've seen a few posts posts where it said that would be risky of computer shutting down while playing(not sure if I saw this in a gtx 1070 post or 1080). And I'm even more unsure about if the GPU is going to fit inside my desktop considering the sizes.

Here is my computer build

Alienware X51 R2 Base

4th Generation Intel Core i7-4790K Processor (Quad Core, 8MB Cache, up to 4.4GHz w/ Turbo Boost
-16GB Dual Channel DDR3 at 1600Mhz (2x8GB)
-Alienware Standard USB 2.0 Keyboard (English)
-NVIDIA GeForce GTX 960 with 2GB GDDR5
-WLAN Card DW1550 Driver
-2TB (64MB Cache) 7200 RPM SATA 6Gb/s
-Windows 8.1 64-Bit English
-MOD,LBL,FGA045,UPC437,X51 R2
-Slot-Loading Dual Layer DVD Burner (9.5mm)
-Dell Wireless 1550 (2x2 11ac combo with Bluetooth)
-US Power Cord
-System BOOT for Windows, AW51
-Resource DVD windows 8.1
-Placemat
-AlienFX System Lighting - Nebula Aqua
-Alienware 330 Watt Power Supply
-Windows 8.1 DVD OS Recovery(English)

I'm going for a new GTX 1070 but I still don't know which model will give me the appropriate size ,and are there anything else that I should be aware when upgrading ? (I knew about the dual 6 pin cable to 8pin will be needed as well.) Thank you !