I've installed a new Epox motherboard into a '90s vintage Gateway midtower ATX case. My problem is that the connector the Gateway case provides for the power switch and LEDs is a single, dual-row multipin plug. It will not attach to the motherboard header which appears to be designed for the standard LED cable set that has individual plugs for the power switch and LEDs. I can't even test the motherboard because I can't turn it on. Do I have to get a new case, or can I somehow adapt the Gateway connector to the motherboard?

If you can get the pinouts for the motherboard's front panel connector, I can get you the pinouts for the cable. Using that, you can adapt the two.

Otherwise, you can get a different cable and adapt it to the control panel assembly on the front of the case.

You could remove the wires and then put each wire into a jumper. Then arandge them so that they work.

OEM's have been known to use proprietary power supply connectors. You may need to buy a new case or power supply in order to install the new motherboard.

The problem isn't the connection to the power supply--it's the connection to the power button and HDD activity light.

I know this cable, and I can tell you which pins are which. Following are the pinouts for that cable.

Notice the one filled-in hole on the cable--this is pin 14, the key that prevents connecting it incorrectly.

1 HDLEDPWR HDLEDPWR Pulled up to Vcc through 330ohm resistor
2 BLINK-GRN GONE-2_SLEEP* and
MESSAGE_WAITING* Routed to both GPIO ports and PIIX4
3 HDACT* HDACT* Routed from pin 39 of primary and secondary IDE ports. Signal pulled high.
4 BLINK-YEL GONE-2_SLEEP* and
MESSAGE_WAITING* Routed to both GPIO ports and PIIX4
5 Ground Ground Routed to ground
6 SWITCH_ON SW_ON Routed to PWRBT* signal on PIIX4 and pulled up to SB3V
7 FP_RESET* FP_RESET* Connected to motherboard PWRGD_ITP signal (power good) and pulled up to Vcc3
8 Ground Ground Routed to ground
9 Vcc Vcc Routed to Vcc
10 FPSLP COMATOSE* Routed to SMBALERT/GPI11 on PIIX4
11 IRRX IRRX Routed to IRRX pin on SIO
12 FPSLP_PWR N/A Routed up to Vcc
13 Ground Ground Routed to ground
14 KEY
15 IRTX IRTX Routed to IRTX pin on SIO
16 Vcc Vcc Vcc

Basically, connect pin 6 (SW_ON) to the ON or SW_ON or SWITCH_ON pin on the motherboard.

Connect at least one ground from the cable to one ground on the motherboard.

I had to do this on one board, and was able to get the system to power on. Because of the alignments, couldn't get the HDD activity light to connect, but it's possible.