hdmi cable = smoke from power supply

[adamsoundSTL]

so I had my ga-x79-ud5 build almost totally done, just sorting out a second monitor through the gt520.

ordered an HDMI monitor, and hooked it up with a borrowed hdmi cable from our home theater setup. Worked great, two monitors, YAHOO.

however that 6' cord didn't quite reach where I needed to, so I picked up a 15' cable today, shut down the machine (running the one DVI monitor), plugged in the monitor and the cable, and when I powered it up there were sparks and smoke from the power supply area, and now it won't turn on (obviously). When I turn the power supply switch on, the power light on the CPU turns on but the machine won't boot and no fans run or anything.

I have a new power supply on order, but I'm paranoid about what could have caused this to happen. The monitor was plugged in to a different power strip (as I had to move it to my desk) but that new strip has other peripherals including the main monitor on it.

So could a bum hdmi cord have caused the problem? Something else? I really don't want to blow another power supply.

I'm also terrified that some other parts got fried, but I guess I won't know that for sure until I get the new supply and can trouble-shoot with it.

So, anything else I should safeguard against before trying again? I have another hdmi cable on order, which I'm hoping is higher quality but who knows.

Any reassurance or horror stories appreciated - what's my best case and worst case scenario for collateral damage here?

Thanks.

 

[adamsoundSTL]

I have realized one other thing that may be a factor when thinking through this more.

I bought a 3TB external hard drive to serve as a backup for all my assorted external hard drives (I do audio work so I have lots of external firewire drives that need frequent backup). My computer has been ON for several days, including being on when I plugged in and set up that external drive. I'm 99% sure it's been on since then, backing up or doing some other task overnight or during the days.

So this would be the first boot with that USB 3.0 external drive hooked up. It's a Seagate drive, seems high quality but it doesn't have a power switch - I guess it just mounts when there's power.

Any chance that drive was a source of the problem?

THANKS

 

[oiwjmrof]

I recommend you get a 3-prong outlet tester and check all of your outlets. Or see
if you can find a knowledgeable friend to help you check them with a voltmeter.

If you have hot and neutral swapped on an outlet and/or unconnected safety ground,
you may be shorting hot to ground when you connect the HDMI cable between the
equipment on different power strips. This can be a serious problem.

You may have just had a bum ATX supply go out at a bad time but if it's a wiring
issue, it will happen again. The second time you might not be so lucky and only
lose your power supply. If it does happen again, please go right away and hire an
electrician to check your house wiring.

Unlikely that it's the USB drive. Good luck!

 

[adamsoundSTL]

thanks! checked the outlets and they all check out - hot is hot and cold is cold, and hot-to-ground = connection. That being said I have two circuits down here, and it looks like on my first connection (where the machine didn't blow up) I had everything on the same circuit, and when it did smoke I was across the two different circuits, which it's possible have a different ground.

The odd thing is that my two monitors and a usb hub and some other etc stuff for the computer have always been running off that other circuit, so I'm not sure why this would just happen now - is there something in the HDMI connection that's more connected than a VGA or DVI cable?

in any case thanks for giving me something to try!

 

[adamsoundSTL]

any chance that it was the cable itself?

 

[oiwjmrof]

The main concern in any of these cables (USB, HDMI, DVI, VGA) is just the outer
ground shield which can carry a lot of current if you have a fault somewhere
in your AC wiring.

If you've got a voltmeter, you can try plugging the cable in on one end, then at
the other end leave it unplugged and measure the voltage from the outer ground
shield on the cable HDMI plug connector to the outer ground shield of the PC or
monitor HDMI receptacle connector.

Set the voltmeter to AC voltage mode. If you see any voltage (say, >1V), it's likely
that the cable ground will short current across the equipment when it's plugged in.

Or another way to do this is to get an extension cord and measure neutral-to-neutral
and ground-to-ground across the two circuits with everything else unplugged. Again,
if you see a voltage difference, you should call an electrician.

 

[adamsoundSTL]

very helpful, thanks!

the plug-to-plug between circuits I can manage, will make sure I do that before installing anything else in the box!

I looked up an hdmi diagram and there's 5 "shield" connectors, so I guess I could measure pin-to-pin across any of them from cable to socket on the video card?

thanks again,

 

[adamsoundSTL]

everything looks good circuit-to-circuit, something like .1V ground to ground, and regular voltage everywhere else.

If I can sort out the physics of it I'm going to try testing pin-to-pin on all the "shield" pins on the hdmi cable and port later.

Otherwise I guess it was just a poorly timed fluke?!

 

[adamsoundSTL]

also I just noticed you said this could be the case with VGA or DVI, too, and I've used this exact combination of circuits and power adapters and monitors with my old MacPro and never had power problems. Starting to suspect that cable, though it wasn't bargain basement by any stretch...

 

[adamsoundSTL]

FYI and fwiw, machine boots fine and seems otherwise unharmed. Can't determine what pins to measure to check for ground on the hdmi cable, but checked it for continuity at least and it's fine.

Quite nervous about "troubleshooting" this problem as I don't want to see another power supply go down. Ordered a new triple shielded cable and will try with that cable and plugged in to the same circuit (which I did by chance the first time) when it arrives.

however ANY other troubleshooting or things to check for would be greatly appreciated. thanks so much oiwjmrof for your help so far.