Blaster Z Sound Card on optiplex 990 Mt

Dell uses custom (proprietary and undocumented) connectors for the front panel.  

Best option, get extender cables that will reach from the rear to the front for Headphones and mic and use them.

or the AE9

if no cash for nicer parts?, why not $3 just run cables to rear and to front, they do sell cheap extender cables.

for example headphone/mic.   (there are vast solutions but you did not state a goal, just how to make a jack work. what must work do tell this please. if USB needed buy power USB hub box, x10 better that.

They even sell USB hubs with sound onboard, for phones mic.  

even more fancy below..  yes, endless sound/audio toys exist some very serious. per below. and better.!

I am confused that jack you POINT to is front panel-I/O,

what do you expect to work there, unstated, but sound will not work there, using your BLASTER CARD.

mic in, and phone out,  when card is active it takes over all sound duties, I think,, and very huge labor to learn.

Is your goal that just front panel 2x 3.5mm mick and phones?  not stated. yet.

is front panel actually needed?

buy a sound card that has one as an option. seen at end of page 2. from same company.

also know there is no ATX standards for this,,,,, its wide open this, audio ports , vary wildly, and a good thing.

the audio ports are 100% free license designs, same goes for the front to rear auto switching methods.

no PC made has standard but some have MFG standards for classes of PC.  only they use.

some even document this like the great  ASUS.com but not dell, if you google scan you find others trying.

is that connector 34 pin, never post on this topic lacking that fact there is a 40 pin too.

the 34 pin is here, and MAY match yours. IDK.  not stated what you have. pin 1 is square pad.

http://www.pcdied.com/intel-magic/Dell/790/790.html

also a secret , I DO NOT KNOW how the in- and out detect works, as see above.

40pin half hacked,here,  for sure power on works.

why not get a better sound card, like this.old card. (new is this, newer )

"Creative Soundblaster Live Audigy sound card with a front panel mount that has RCA/phonoplug inputs, digital optical audio input and output, jack plug headphone output, jack plug mike input and SPDIF input and output on RCA sockets.all conveniently mounted on the front panel of the tower body."