Hey guys, is it safe to use the computer case in a LED circuit. Example, Im redoing all the fan LEDs and changing them to UV LEDs, BUT I want all the LEDS going through one circuit through a switch. No to safe time and wire, I want to complete the circuit by grounding it to the case, is that ok?
personally i wouldnt do it, as the smalest static/spark can cause damgae to any pcb/electrical hardware. i would daisy chain the led's to reduce wire usage and that way it would be safe.
The computer case isn't like a car chassis, you shouldn't use it like a ground. It's only grounded for safety.
WUT? AFAIK, the only reason pc manufacturers use steel cases, is to shield noise emission and absorption. Many people run non steel cases without any stability or safety issues, as the earth cables from the psu are sufficient to earth everything. They might possibly have a bit more interference noticeable on nearby radios, phones, etc, and overclocking might possibly not be as successful in an environment rich with transmitted electrical noise, but that's about it. A computer case isn't like a car chassis, in that it isn't used to eliminate the cost and weight of earth wiring. Feel free to use a pc case as an earth however, for it is a massive redundant earth path. Sure sparks can cause damage to pcb hardware... and a securely earthed line on the pc case, has just as much chance of causing a spark, as would a securely attached earth connection anywhere else in the pc. TL;DR: Feel free to use the pc case as an earth, you just need to attach any earth leads securely to clean bare metal of course.
I wouldn't do it either. You can use a single switch to switch on and off all your LEDs. Just run a positive or ground wire to the switch and back down to your distribution point. Providing you have a switch with enough current handling for all your LEDs it'll work fine. You don't need to switch both wires.
Keep in mind that you would be connection the PSU/motherboard ground to the mains EARTH wire...I am pretty sure this is a big no no...
The much confusion about electricity in this thread. You know all those screws that attach the motherboard to the pc case? Well unless you are screwing every single one of them into plastic stand offs, then your motherboard's earths are all being directly short circuited into the case, which is not just the earth of your psu, but also connected to the actual earth via the power point, as in the planet we live on, it's all connected!!!! This is how the government can hack into your pc!!!!!11111111111 Ok I'm joking about that last part, but seriously, almost every pc out there has at least one screw connecting motherboard earth directly to the case, which does actually connect deep into out planet earth via the AC power point on the wall. All those black earth wires plugging into everything inside the pc, as in the motherboard, gpu, hdd, dvd, fans, etc, they are all connected to the earthed case of the psu, which is also screwed into the pc case, so plastic motherboard standoffs aren't enough to prevent the motherboard earth from connecting to the case earth anyway, you'd have to insulate everything! It's a good thing to screw in the motherboard to the case btw, this way the metal motherboard bracket is a lovely noise shield for the motherboard, and even helps take some of the current load away from the earth wires of the psu.
So in theory you should be able to hook up a multimeter red (+) to the 12v on a molex connector and the black (-) to the case. This should complete the circuit to ground giving a 12v reading yes?
Yes, definitely, assuming the black(-) wire is securely connected to a bare metal section of the case. There's a heap of ways to securely attach an earth lead to the case, the easiest is probably to use a crimp on an eye connector and screw it on using any one of the many existing case screws.
