Ok first u should unplug everything from the back of your computer. Next u should open the case facing you. There should be 2 screws hold the top plastic to the bottom plastic. One in the front and back corner.
Take out the 2 screws u see on the side. This will let u take the top plastic off while the bottom plastic is still mounted.
U can take the bottom plastic off by unscrewing the 8 bolts that u see connected to it if u like. I didn't have to do this because of the tools i used.
Next u should take off the usb cover. To do this leave the usb cover flat. Put a little pressure till the side facing u comes out.
Make sure u don't lose the spring that is under your usb cover.
Next you should apply some pressure to the top plastic pushing from the side and push up. This way u do not have to tare down your comp to get to the left screws.
Once the top plastic is removed u will see the bottom plastic still mounted.
What i did here was place my fan over a spot where it wouldn't suck air from my memory fan blowing in. Then i scratched an outline of my fan to know where to cut the plastic out. I cut the plastic with a dremel tool. If u dont have the right tools to do this when the bottom plastic is still mounted in. You might want to take it off. Some of the plastic is thick.
Run the wires to the front. There is a little port hole witch has a screw that u can put your wires threw.
Here is the hole open. Do not forget to close it back after the wires are ran. Don't screw it back down all the way. You can cut/ pinch the wires enough that it might ground out and fry something. Make sure you don't do this. Leave it open enough for the wires to have some space to move. You should be able to move the wire with your finger after it is screwed back in.
Now the fan should be mounted in a spot u wanted it to be. I used zip ties to hold mine in place. I didn't want to add extra holes into my case. I think its easier to do it this way because of the space from the heatsink to the cage. If your going to drill holes to mount the fan with screws then u will need to remove the fan board.
After all of this you should have your fan mounted. If not Keep going u will get it. I use my top fan for exhaust. I put the back fan that is connect to my radiator blowing in. My temps are about 32-40c with my fans at 3%. I think with 100% it would push 30c on idle. On load I'm not sure yet i need to test it out. After you get your fan or fans mounted make sure you put everything back where it was. This is the easy part
Also seeing as dell has a 4 pin fan connector u can get a fan splitter cable to connect both fans to the System fan. I cant seem to find the website that i bought my splitter cable from. I will find this later and edit this post. Next project to install a fan controller on the top of my case.
Lets hope its a lot easier then adding a top fan.
100% fan speed. temps on idle.
Intel Core i7 980 Extreme 6C (3.33GHz, 12MB Cache) OC to 3.7Ghz stable
stock 6GB Triple Channel 1333Mhz DDR3
stock Alienware High-Performance Liquid Cooling
Windows 7 Professional 64bit
stock 1.8GB NVIDIA GeForce GTX 260 GDDR3
Sound Blaster X-Fi Titanium