Powering circuit with relay off of 5v usb header on motherboard

[Dewst3r]

Hello, I am currently in progress of making a circuit that has a relay in it. I was planning on the power of the circuit to be coming from the usb header on the motherboard since the motherboard I have supplies power to it when it is in the off state. With a switch, it would activate the relay in my circuit. I understand that the relay's reverse polarity can be harmful to other electronics in the circuit (in this case the motherboard) if not dealt with properly. I have a diode that handles that extra voltage from when the relay switches back to its default state. My question is: Even with the diode in place, will my motherboard still be at risk for damage with the relay? Right now I am using AC to DC 5V wall plug to power the circuit and I would like to move it onto my computer for my convenience. Note that it works fine with the wall plug and I have tested it. There is a transistor as well. Picture of circuit attached.

What is the circuit that I have been talking about?
It is a circuit with 2 flip switches and a key switch to turn on my computer. It was something fun with no practical purpose. I am using power instead of using the circuit to directly short the pins because the switches have LED's in them which I would like to have illuminated when flipping on (adds to the cool factor lol).

This will be mounted on the top of my case. Picture also attached.

If I didn't explain myself well enough, which is likely, I will be actively watching this post for 10 minutes after, and every now and again after.

Edit: changed time frame that I will be looking at this

[ELSknutson]

Your better off using a molex connector.

[Dewst3r]

Your better off using a molex connector.

Will that supply power when the computer is off....I never even thought of using molex

[ELSknutson]

Will that supply power when the computer is off....I never even thought of using molex

As long as the power supply is on it should. I know mine does I have a plug to test LED strips us ring the yellow and black12v in believe the red and black is your 5v. I just cut off a jumper I had that had the molex end.

[ELSknutson]

You can also use a 120v av wall plug that converts to DC like a cell phone charge you just have to find the right size you need cut off the end and use the 2 wires.

[Dewst3r]

As long as the power supply is on it should. I know mine does I have a plug to test LED strips us ring the yellow and black12v in believe the red and black is your 5v. I just cut off a jumper I had that had the molex end.

Ok cool that sounds pretty good...would you suggest that this would be a safer bet in my situation than using the usb header on my motherboard? I would assume the power supply (Corsair CX500M) would have some sort of surge suppression past the power coming directly from the wall. Once again, I just want to be 100% sure that nothing will get damaged and that the diode will succeed in taking all the excess voltage from the relay.

[Dewst3r]

You can also use a 120v av wall plug that converts to DC like a cell phone charge you just have to find the right size you need cut off the end and use the 2 wires.

That's what I'm using right now...I just wanted to see about moving my power source to my computer just for ease of use.

[Electronics Wizardy]

Most psu have a 2-3 amp standby rail on the psu so that should be more than enough. Also i notice your using a zener diode, you should be using a normal diode.

[Dewst3r]

Most psu have a 2-3 amp standby rail on the psu so that should be more than enough. Also i notice your using a zener diode, you should be using a normal diode.

I am using this diode: 1N4148 http://www.vishay.com/docs/81857/1n4148.pdf 

That is a datasheet that I found online.

What is the difference between the two diodes?

[ELSknutson]

I can see the sheets I'm on my phone

[Dewst3r]

Hey I decided to go with an optocoupler....saves the worry about the relay completely...works with 5V and a resistor perfectly. Thank you guys.