Question Does anyone know how to turn on this old HP Elite 8300 motherboard without a power switch/case?

[Crabodactyl]

UPDATE: Partially solved. See bottom of post for updates.

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I recently acquired one of the cheapest LGA 1155 motherboards I could find on eBay for a budget build. I did a similar build with an old Intel board recently and was able to jumpstart it by shorting the power switch pins after locating them using the manual. No problem.

The trouble is, (A) I can't seem to find the power switch pins to jump on this old, proprietary HP Elite 8300 motherboard. Also, (B) I'm not sure if it's fully powered since it uses weird power connectors. Here's a pic:

Those labels are taken from the official HP "Illustrated Parts and Service Map" for this board.

I have the 4-pin CPU power plugged into my Seasonic 400W PSU, to power an i3 3240. Also have 2x4GB DDR3 PC3-12800 RAM in the two slots closest to CPU.

I have the 6-pin "PWR" or "Main Power" plugged in.

I have no idea what that strange 6-pin "PWR CMD" or "Power Connector" is.

There are no signs of life on the board when PSU is switched on, and I can't figure out which pins I should even be able to jump to power on (in the event the board were fully powered.

So to sum up:

1. I don't know if I have the board fully powered, and
2. I wouldn't know what pins to jump to turn it on if it were fully powered.

Any thoughts or suggestions would be very much appreciated!

-----------UPDATE-----------

I think I've solved the problem of how to power the board - need to use a 24-pin to 6-pin power adapter like this one. Still don't know how to turn the thing on without a case switch though.

-----------UPDATE 2-----------

I think I found the header I'll need to jump - the black header in the lower right corner is the power button/LED header. I still don't know precisely which pins on the header to jump, because they're not individually color-coded or identified in the manual.

 

[Crabodactyl]

Doing a little more research on this, I think I may have cracked the power supply issue. I think I need a 24-pin to 6-pin power adapter like this one to get the board fully powered. Lesson learned on that one.

The question still remains - how do I start this thing without a case and power switch? Does anyone know if any of these pins can be jumped to power on?

 

[Crabodactyl]

Another update - I think I found the header I'll need to jump - the black header that's at a 90-degree angle from the other headers in the lower right corner is the power button/LED header. So I imagine if I jump the right couple pins there (hard to know which two pins because they're not individually color-coded or identified in the manual), then it can power on.

But which two pins to jump?

 

[rickypicky5]

Typically the "power button led" pins are just for the LED associated with the power button, not the power button itself. There should be 2 separate pins, next to each other, that are the actual "power" button pins.

 

[Crabodactyl]

Typically the "power button led" pins are just for the LED associated with the power button, not the power button itself. There should be 2 separate pins, next to each other, that are the actual "power" button pins.

At least with some older motherboards I've jumped before, the power button and power LED pins are all on the same header. I suspect that's the case here as well. Based on some responses on the Linus Tech Tips forum, I think I'll try grounding the various pins on that header using a multimeter (once my adapter comes in and I can power the motherboard). I expect grounding on of those pins should do the job.