A couple weeks ago my network router at home finally died (it was a Linksys WRT54G), but I certainly got my money out of it (I got it when it first came out which was probably 4 or 5 years ago). Every light on it flashed, which couldn’t be good… so I replaced it.
Long story short is I bought another one (same model) and just swapped it out with the new one (using the old power supply). Well it was doing some weirdness every 24 hours or so where the power light would flash and it would loose Internet connectivity (all other lights were fine) and if you unplugged it and plugged it back in, you were golden again. Everything I looked at online was saying a flashing power light meant the firmware was screwed up (I didn’t change anything with it). Finally I decided to look closer at the power supply… even though it was the same model, the new version runs on 12 volts and the old one ran on 5 volts.
So I guess you can run a 12 volt piece of equipment on a 5 volt power supply and it will work (for awhile anyway).