VOGONS

How do I know which header pin goes where on my motherboard if there's no manual for the case?

Topic actions

First post, by Gamerappa

Posted on 
User metadata
Rank Newbie
Rank
Newbie

I am in the process of building my first retro computer. The motherboard is a Socket 939 Tyan motherboard (Tyan Tomcat K8E S2865G2NR), while the case is a generic no-name "AMG 3000/EZ4000 Multimedia Computer System" case from Taiwan. There is no documentation regarding this case, all I can find online are other retro or sleeper builds that just so happen to use this case.

There are two sets of wires, the front panel header wires, and what appears to be a mix of front panel USB and headphone port wires. I have managed to figure out most of the front panel header wires, but there are two remaining that I don't know what they're supposed to be: A green wire and a white wire.

I think the green wire might be for the +5V standby pin? But i'm not sure. The white wire is a complete mystery to me. As the motherboard was intended for workstation/server use, there's also additional pins which I believe are optional (SDA, SCL, NC, Chassis intrusion).

The USB/headphone port wires are also a complete mystery to me. There's multiple that are labeled "Port +" and "Port -", but a few others simply labeled "+" and "-". I think this is from an older standard? The case is from around 2002 while the motherboard is from 2005. Before I do anything stupid and potentially short out the motherboard, I'd like to know first beforehand.

Reply 1 of 3, by wierd_w

Posted on 
User metadata
Rank Oldbie
Rank
Oldbie

This is by no means universal, gospel, or reliable:

'Often', the green/white pair are the 'Power LED' indicator pair. It's often split up like that due to some board makers using a 4 post header for powerled (mostly on old baby AT boards), and some using 2 post instead.

Follow them in the case to where they end to be sure.

But, if color coded... 'ususally'

Red/white = hdd led
green/white = Power led
orage/white = power switch
blue/white = reset switch

different case makers do things differently. it is not at all uncommon for all the cables to just be black, with white silkscreening on the dupont connector housing for what is what.

for retro cases with color coding though, that's 'usually' what is what color.

if your cables are unlabelled, after sussing out what each pair is, get a roll of cloth medical tape, and make some tape flags on your cables with it, then label them using a fine point sharpie.

Cloth medical tape ages better than masking tape.

Reply 2 of 3, by Gamerappa

Posted on 
User metadata
Rank Newbie
Rank
Newbie

That seems to be the case. I checked again, and the ones that were plugged in perfectly matched your description. So this is definitely the power LED. No idea why these are separate compared to the other ones which are combined, but oh well.

I'm still not too sure on the USB/headphone header wires, though.

Reply 3 of 3, by st31276a

Posted on 
User metadata
Rank Member
Rank
Member

Older boards had keylock and power led together in a 4 or 5 pin header, newer ones power led on 2 pin header. I even saw a pentium era board with power led straddling a pin on a 3 pin connector. Thats why they are apart from each other.

Go to top of page Go to top of page
Back to General Old Hardware
Close window
Close window