I burnt my hand on the massive heat sink for the CPU and realized that the whole computer is really hot, after a quick and technical airflow test (sticking my hands in different places) I figured out that the single massive fan at the front isn't pushing enough air out the back vents, thankfully it's all pretty clean inside since the fan pulls in from the front vent that is six inches off the floor, rather than the usual floor level ones.
Step 1: Tools and Materials.
One 10 or 12cm fan, I nicked one from an old power supply but if you want control over it get a smart fan, I have found that there isn't any appreciable noise difference and it's quieter during normal operation since the massive fan at the front isn't going at full speed.
A pair of wire clippers or a molex jack, I had to use wire clippers since I had no jacks around to fit the spare one.
Some tape or heat shrink for insulating wires...
Step 2: Opening Them Up.
Step 3: Adding Our Fan.
Unless you actually have a need to remove the black air box you really shouldn't, the heatsink for the CPU is attached to this and you'd need to re-apply thermal compound to it after removal. For reference the box is removed by unscrewing the two starhead screws near the front of the box, it then hinges backward towards you and pops off.
The back grille is relatively clear and free of obstructions and is a good place for the fan, being the main exit for air we basically augment the original system without fundamentally changing the airflow characteristics.
If at this point you have a few fan clips that could be used to attach the fan to the grill I'd suggest using them.
If not then you'll be using the same quick and dirty method I did, done right it's completely secure and very flexible.
Before touching anything inside the case though we need to ground ourselves, I tend to touch the copper pipe on a nearby radiator and again on the frame of the case, to make sure I've been grounded completely.
Once safely grounded take your wire and tie a knot near one end, pull the rest through a hole in the fan and loop across and back through the next hole and through the grill, pulling it tight as you go, once you've come to the last corner needing secure by pulling it through the an and grill, put a loop in through the grill and tie a knot on to the grill.
Step 4: Wiring It Up...
If you have a connector then job done.
If not you'll need to either extend the leads of the fan by soldering on some wires, if you solder on some wires, remember to use heat shrink wrapping or tape to insulate connections, just in case they hit the mobo and cause a short and possible destruction in the computers squishy innards.
Hook it up and test it's running, to figure out how to make the most use of a single fan I did all of this modification with the computer running, you needn't risk doing so since I've done the dumb stuff on this one.
Step 5: Close 'Er Up and See the Difference.
The results were huge differences...
The HDD temps were down from 69C to 48C, huge can, since they're under the big fan tunnel they get minimal cooling and have a lot of heat buildup, depending on usage the CPU heat went down by 4-9C which is very good and the speed was no longer sitting 334 mhz below spec, which is nice to know.
Next step will be augmenting the rather inadequate 512mb of ram and bringing it up to 4GB, also replacing the dead writer drive and adding a TV card and a few internal USB slots to keep the permanently plugged in peripherals out of the way.