Weird problem with new system built yesterday

[Primitivus]

Yesterday I put together a new system for a friend who works with audio/video. The specs are:

Cooler Master Centurion case
Gigabyte K8NF-9 Ultra
Athlon 64 3800+ X2
2x1Gb Twinmos DDR-400 RAM
Sapphire X1600XT
Western Digital 250Gb HDD1
Seagate 80Gb HDD2
External 200Gb HDD3
NEC DVD-RW
Echo DARLA 20 audio card 1
Creative SoundBlaster Live audio card 2
Wireless antenna + wireless DSL modem

After everything was set up we installed a fresh copy of windows and started installing all the necessary drivers. Then he realised he didn't have any drivers for the wireless antenna so he couldn't connect to the internet to download any updates. So we plugged in an old USB dial-up modem he had lying around to get the drivers for the antenna. As soon as the USB cable of the modem was inserted in one of the two front USB ports of the CoolerMaster case sparks started flying! The old modem was literally fried and thick smoke started coming out of its insides. After that when he re-tried it the USB port seemed to work, it recognised that sth was connected to it but couldn't say what since the device was dead.

I've never had a similar problem in the past and I've no idea what could be causing it. Do you think it could be a problem with the modem, too much dust or static electricity built up over the months it hadn't been used? Or maybe sth to do with the USB port and therefore the mobo, maybe too much voltage going to that particular port for some reason? Or maybe sth else entirely? Any tips would be appreciated.

 

[Scout]

Sort of sounds like you may have your USB cable plugged into your 1394 Firewire port on the motherboard. The 1394 plug looks the same but has a 12 volt lead where the USB has ground pins. That would certainly fry your modem!

 

[Primitivus]

Thanks for the reply but that's not the case. The sockets are colour coded, purple for Firewire and yellow for USB and we haven't made a mistake there. A while ago my friend told me he tried a USB mouse on that same port and it also was fried...

 

[mesarectifier]

If that port has fried multiple devices then surely the answer is obvious?

 

[kev22257]

Are the ends of the cables for the front ports one block that's keyed to go in a specific way or is it like my Antec case where each pin in a wire and you have to figure out which one goes where. If that's the case you might have a wire in the wrong spot and have sent voltage where it doesn't belong...

 

[MrsD]

Id say you hooked up the ports incorrectly to the mobo. Maybe did some permanent damage.

 

[slim142]

Maybe your mobo loves fireworks ^^

Just kidding

 

[spentshells]

is the modem usb2.0 compliant ?

cause if its not then you're were running to much voltage

just a guess yer usb modem was older ?

if not disregard

 

[michaelahess]

too much voltage??? what are you smoking, it's 5v regardless of v1.1 or v2, ever hear that they were backwards and forwards compatible?

if the case has four individual pins for each usb port, make sure they are vcc+ (usually red) D- (usually white) D+ (usually green/yellow) vcc- (black)

obviously start at pin 1 on the header

otherwise check your ports and make sure there is nothing touching the contacts on the case, no metal shielding for example

try another usb header on the mb

 

[Primitivus]

They're not individual pins, it's a little block that's designed to go into a yellow (USB) socket. And obviously on the mobo USB sockets pin no.7 is missing as is usually the case and the corresponding hole in the plug is also blocked so you can't connect it the wrong way around. Thanks everyone for taking an interest and for the logical replies but unfortunately the problem is still resisting our efforts. I've built several systems in the past and I know what I'm doing regarding hooking things up correctly. So, I think we'll RMA it since we're running out of USB devices to fry :?

 

[ET]

Before you RMA anything try testing the voltages right from the pins on the MB. Also make sure that the cable to the USB port is not "HOT" from a mini circuit board failure, (some MB's have a Mini circuit board in the front of the case to control lights, power, etc.) In other words, is the cable going to your USB port a stand alone cable without crossed leads, (test with Ohm Meter.) and does your MB USB pins show the proper voltage and ground?