PLEASE HELP! External HDD cuts all computer power

[Ricster-a]

Ok so i have a Seagate 1TB External hardrive which is 3.0 USB i have it plugged into my computer which is also 3.0 even though this wouldn't make a difference but i also tried it in 2.0. My system is:

XFX 650w PSU
WD 1TB Caviar Blue
Corsair vengeance pro series Ram
COrsair 300r case
Gigabyte H87-HD3 Motherboard
CM 212 evo CPU cooler
i5 4670 CPU
Samsung DVD-RW drive
1 SP Corsair Fan
6 AF Corsair fans

When it switches off there is no blue or black screen it just dies straight. In the same way if you were to pull the power cable from the PSU.

I have had this mainly plugged into the rear USB slots but have tried the front also. This HDD was working for a month or so with this computer the problem has only just come up now, The external HDD works fine on my other computer.

I have tried error checking the external drive, renamed the drive letter paths. Any ideas please?

 

[Ricster-a]

I also tried it in my samsung tv's usb port it had a little problem saying it was disconnected but without touching it connect back and work fine. I did a virus scan also with Kaspersky which came back clear.