Computer stuck in autoreboot cycle

[Ben_M]

Recently, I built a gaming computer, and it has run pretty well. The only problem I've had is that the GPU runs hotter than I'd like (85C under load). So, after about a week I decided I'd get two Corsair 140MM fans and a NZXT Sentry Mix 2 fan controller. I installed the two fans, plugged them into the fan controller, and plugged in the fan controller using the both Molex plugs. Upon boot, my computer has been stuck in an on-off boot cycle. Power on, stay on for ten seconds, power off. Power on, stay on for ten seconds, power off. Power on....
Unplugging the computer stops the cycle, obviously, but that doesn't fix the problem. Unplugging the fans and fan controller does nothing to fix the problem either. Can anyone help me? My computer won't even POST.

My computer specs are as follows:
Intel i7 3770 /w stock cooler (Hits ~45C under max load)
Gigabyte GA-B75M D3P Rev. 1.0, BIOS updated to version F7
PowerColor R9 380 4GB GPU
12GB Kingston DDR3/1333 RAM
Samsung 850 EVO 256GB SSD
Seagate 500GB 7200RPM HDD
Corsair 750M PSU
Corsair 200R case (Windowed)
Windows 7 Home Premium 64 Bit

Thank you all for any help or thoughts on the matter.

EDIT: For some reason, the computer will boot if I remove the GPU and boot on integrated graphics.

 

[Nodyjoe]

It sounds like your PSU is having issues with keeping the card fed after adding the fans. have you tried to unplug the fan controller and seeing if it boots up still? Also if your GPU is getting up to 85 degrees C try reseating the cooler, and replacing the thermal paste.

 

[Zaweri]

Yeah, that PSU is a weak one for your setup. From what I have heard and read the R9 380 is quite the power hungry card.
Anyways, you should replace the paste with some NT-H1 from Noctua. The stock thermal paste is sometimes bad in GPUs.

 

[Ben_M]

Thanks for all your input. I appear to have fixed the problem with you advice. I reseated the cooler (and GPU) and everything started working, including the fans and controller.
The thoughts on the power supply were interesting, so I did a bit of research on the matter. My power supply should be quite adequate for my system. As Tom's UK noted, under full load, the 380 consumes just under 300W at full load. (http://www.tomshardware.co.uk/amd-radeon-r9-390x-r9-380-r7-370,review-33233-9.html) Assuming my CPU draws double the TDP, I'm only at 454W. SSD and HDD, with RAM should be less than 50W together. In this worst-case scenario, I need 504W--the PSU is 80+ rated, so I'm getting about 600W, or an excess of ~100W over the worst-case scenario.
So, this is hopefully just a freak misseating issue.
Thanks again for all of your help!

 

[Nodyjoe]

No problem dont forget to pick a solution.