Don't know how far along you are in the rebuild, below is just the order in which I do it. If you need some instructions for the removal of the heat-sink/fan and CPU? let us know.You have the various Manuals for reference but suggest you proceed in the following order. Please remember to turn of the power and take anti static measures when working on the computer.
> If installed, remove and replace the I/O shield in the case with the one supplied in the MB box.
> Alter/install fans if required.
> Install the PSU.
> Check carefully the stand-offs on the MB mounting plate inside the case, the number and pattern must match exactly the screw holes in the MB, no extra ones.
> Install the Optical Drive, (i prefer the second bay down allowing installation of something like a fan controller later).
> Place the MB on a clean piece of cardboard, a little larger than the board.
> Install the CPU.
> Check there will be thermal interface material on the heat-sink plate (usually a pre applied pad/strips on stock cooler) or IF NOT PRESENT, APPLY YOUR OWN to the top of the CPU as per instruction that came with the TIM.
>Install the CPU heat-sink/fan.
> Connect the CPU fan plug to the CPU fan header on the MB.
> Install the RAM, refer MB Manual for the correct slots.
> Carefully lay the MB in the case checking screw holes and stand-offs are correct. Note the drive bay/s that are at the end of slot/s where the video card/s are to be installed, where possible leave them empty of HDD/s. Makes cable connection easer.
> Lift out the MB, put to one side.
> Install HDD/s,
> Install the MB. refer MB Manual.
> Connect the two power cables to the MB.
> Install the GPU/s. and connect the required PCI-E power cables. refer MB manual for correct slot/s and GPU manual for number of power cables,,
> Install any other add on cards. (check manuals, (some, very few, require software be installed first)
> Run and connect the rest of the wiring.
> If using, connect the mini internal system speaker, ensure the +/- on the plug matches the symbols on the header pins.
> Check over your wiring, OK??
Keyboard, Preferable use a PS/2 keyboard, otherwise connect a USB mouse and keyboard to USB 2.0.
> If using wired Internet, connect to the access point, (router/Modem)
> Connect signal cable first, then power to the monitor and switch on.
IMPORTANT. If your PSU has a switch on the back for selection the voltage, ensure it is set correctly for your AC power.
you are ready to go.
> Plug in the PSU, switch on at the socket and the switch at the back of the unit.
> Press the Power On switch on he case.
NB. Keep all packaging, receipts and any bits left over, Should you have any additional questions, just ask. If you get stuck or are not sure of something, please stop and seek advice