adding a fan to a PSU

i want to add a fan to my psu and i don't want to run a cable into it, does anyone know if i'd beable to solder the wires in?

A lot of circuit boards are designed for more than one fan and have the extra holes for the wires of a second fan. But even if yours isn't, you should be able to fit the extra wires into the existing fan's holes, provided you remove its wires (cut off soldered part, strip, and twist the wires of the two fans together so they'll fit better). Some boards have extra holes for +12V and ground wires, but I don't think you'd want to use them because the new fan would run at full speed/full noise all the time.

do you think soldering the wires to the wires of the first fan would be a solution? either that or soldering the wires to the same place as the first?

I would think that soldering the wires to the old fan wires would work, but I'm not an electician, so wait for someone else to confirm it before opening it up and doing so.

as long as you connect the wires properly then most power supplies should quite happily run two fans from one set of solder points / contacts. The other way is to bend a spare power adapter back inside the power supply and use that. I have hacked up the 4pin square P4 adapter to allow to create a ring main for all my cae fans. The same could have been done to accomodate an extra fan inside the PSU.

I just spliced the new fan to the old wires and it worked perfectly and is now silent.