Is it possible to replace either the NorthBridge or SouthBridge Chipse

Doubtful. Have you seen the leads on those chips?

Although with specialized tools it *might* possible, I am going to go ahead and say that it is not likely.

The data transfer lanes between the CPU and NB / SB are very sensitive and anything interrupting the flow will render the MB inoperable.

If it is actually something wrong with the NB or SB you are better off getting a new board if things such as flashing the BIOS don't work.

Here is a pic of an uninstalled NB. It is an old chip, so there are less pins / wider spacing between pins than would be of a current chip.

http://img.alibaba.com/wsphoto/v0/343385095/G86-771-A2-...

If even a single drop of solder shorted a pin you're done with that chip.

Which is what I meant by leads. I don't know of anyone good enough to put that many tiny leads in the correct holes and then solder them all correctly in a many layer PCB. Doesn't mean he doesn't exist somewhere, but I doubt its 99%+ of us.

Grantewd the chips on the board have to get there somehow I tkink in the actual mking og the board a lot of things are put on by machine and not by human hands. I don't tkink that what you want to do is adviseable . I have RMA'D a few boards to Asus and when you start the RMA process they tell you that they repait the board and under ne circumstances do they give you a new or refurbushed board back ,well every time I have gotten back a refurbished board . So it seems to me that even the board makers don't want to mess with replacing chips on the board. However having said that if you have a board that you are not using or need and you want to experiment and see if you can do it then there is nothing wrong with that just don't expect it to be easy. You might also need specialized tools that can work in small places like a soldering iron with an extremely small tip and special solder , those points on the board are very small and it might be impossible to get pinpoint acuracy.

Manufacturers don't actually solder every pin.

They place all the sockets and dip the bottom of the board into a "solder bath" where every pin on the entire board is soldered at once, and when they lift the board out the solder either drops off or congeals around the pins so they are not touching anything else.

exactly itzdanielp. Since more than a decade already, manufacturers uses solder dip to do it. I highly doubt you can do it manually. Hot Solder Dipping Has Significant Benefits

- Prevents Rusting:
For steel, the hot solder coating prevents the base material from rusting.
- Prevents Oxidizing:
For copper and copper alloys, the hot solder coating prevents the base material from oxidizing.
- Restores Solderability:
Solder by its very nature is solderable, which makes it a desirable finish for electronic component assembly.
- Easier To Solder:
Solder coatings are easier to solder than those of pure tin, since the lower melting point of the solder allows for a variety of heating methods.
- Wear & Corrosion Resistant:
A solder layer provides greater wear and corrosion resistance than that of most base materials.

How motherboards are made inside a Gigabyte factory:
http://www.youtube.com/watch?v=Va3Bfjn4inA

Look from 3:37, you can see the solder made pretty fast by a solder bath. Oh well you don't see the actual bath, but you can see it takes only seconds to do that step.

You can see the dip soldering process here, look from 2:18:
http://www.youtube.com/watch?v=rL2Skdv3zls

The short answer to the OP's original question is NO, you can't feasibly do as you ask. It is simply not practical. Sorry.

I know that with a bios you can,but as far I know for the chips,no.

As far as I know,wish I was wealthy is right.  

Hey everyone thanks for the helpful replies. However I did find out from someone who kindly helped me locate these videos on YouTube.com. From these videos it appears to be possible since in the videos they are trying to replace a BGA with Hot Air Rework Station. Here are some of the links. Please keep in mind that they are not actually replacing either of the NB or SB chips however the SB and the ones being replaced have an extreme similarity in the appearance of the design in the manner the way the chip is seated on a PCB. I believe that it can be done with the right tools and experience and of course having a replacement chip. Sorry for not researching this on YouTube before my post although I did not expect to find anything on YouTube but I was obviously mistaken.


http://www.youtube.com/user/reply4reply#p/u/4/BnkGXjcNz...
http://www.youtube.com/watch?v=A7O7cRowbLI
http://www.youtube.com/watch?NR=1&v=vOr6Gse6BOw

as we all said before, I am not going to call it impossible, but the chances of you (or anyone for that matter) completing a desolder and resolder of either chip *extremely* unlikely.

If you want to go ahead and do it, no one is holding you back, but I hope the hardware you are using isn't necessary, because you probably will have a nice paperweight after you finish.