Lost stereo output (almost)

[Timoi]

Hi, I believe my computer has started outputting nearly all audio through just a single channel.

My speakers are set up through an amp which is connected to my PC through cable with 3 mm jack PC end and split to L/R phono on amp end. I have ruled out a hardware problem because if I connect the 3mm jack to my laptop, altering nothing else in the setup the sound comes out of both speakers fine. Also if I switch the L/R phono cables at my amp the problem switches to the other speaker.

This is why I believe the PC is simply only outputting on one channel.

Next I will explain the almost in the thread title. If I turn the L/R balance to the right (that's the side at my PC that seems to have no sound, of course by switching my phono cables I can make it the left speaker that's quiet) and then turn the sound up at my amp the sound comes through the quiet speaker very faintly and a little distorted. So a little audio still comes through that channel.

I have a Fatal1ty FP-IN9 SLI MB which comes with RealTek audio, which I have just updated to the latest driver but that did not fix the problem.

The RealTek audio comes with the "Realtek HD audio manager" which sits in my system tray all the time. I have just spent the last few hours trying different settings and have tried extensively to tell it that I want it to output in two channels but it won't.

Last to say is that I have just returned home from uni where I have my speakers most of the year. So the last time this PC used this setup was almost a year ago but it worked fine then so I don't know why it is having problems now.

Thanks in advance. Let me know if there is more information I can give you.

EDIT** Did a bit more research thought I would clarify that it is the RIGHT sound that is lost. I learnt that the left sound is picked up at the tip of the 3mm jack and the right at the ring half-way down. My jack must be fine because it works with my laptop but could it be that the connector on my PC is shorting or something so that it is indeed hardware problem. If this is the case what is the best solution? Preferably not a new MB

EDIT 2** Ok I know this is ridiculous seeing as nobody replied to this yet but after convincing myself about 10 mins ago that is was indeed a hardware problem with the female jack plug on my MB I did some research and worked out I could reroute my line out through one of the other female plugs which are meant for surround sound but I have no use for. THEREFORE THE PROBLEM IS SOLVED, SORRY FOR WASTING SPACE.

Hopefully anybody else who runs into the same problem can use this post as a diagnostic tool and hopefully a solution.