in addition to voltage, make sure you are supplying the proper amount of current from your power supply.
I got a 6.4" LCD kit off eBay some time ago that was originally sold by earthlcd.com and I am having an odd problem with it. I hooked it up to one of my desktop PCs (powered through a molex connector) and it was working fine. Then I hooked it up to my CarPC and it wouldn't boot completely since the PS couldn't handle the LCD. So I got an old PS that has the switch wired to it and hooked the LCD up to that, but now it is extremely dim, and is only visible if looking at it from a top angle. Any ideas? Thanks in advance for any help you provide.
Yea, and I used the ground next to that, although the LCD works without the ground - red on LCD to yellow molex.