Can I power two 12V fans using an AC adapter?

I have 3 Xbox 360's, 1 is an old white (badly) modded pro console, 1 is an old Elite, and the one I use is a 250GB Slim.

Since my old modded console is basically an over-sized paperweight, I want to take the fan assembly out of it and build a case for it so I can attach it to my new 360 Slim. Problem is, I'm not sure how to power them. I know for SURE that I want to use a separate power supply rather than piggyback off the xbox's power, so I have two choices - AC adapter, or batteries.

Since they're each 12V .4A (.4A would be 400mA?) fans, I'm wondering how much power I'd need. Would a 12V 850mA adapter power both fans at 100%? Would the fans only use as much power as they NEED or would they just end up using ALL the power the adapter puts out?

I'm kind of new to this whole thing so any help would be much appreciated!

 

The fans together would draw 800ma so the adapter will power them fine.

If the adapter WAS under power it may cause a voltage drop and run fans slower and also the adapter might get very hot depending on the adapter quality.

Also if the slim is working fine I would not mess with the airflow, you might actually choke the internal fan and make things worse for no reason. I know the Fats need extra cooling and an extra fan in the back does help a bit but I cant see how they would help a slim, completely different shape. Don't go against the current airflow whatever you do, the internal fan is blowing OUT the big vent and it needs to stay that way.

 

So I can just splice the wires together without anything else and it'll work? Sweet.

Yeah, I was going to put them on the end of the case, on what would be the top if it was sitting vertical. I'm going to make them blow air INTO the console, not out.

And the reason I'm doing this is that I'm already on my 2nd slim in 2 weeks since my hard drive got fried on the first one when it got too hot.

 

Well, I got it all set up and the fans are SO freaking loud at 100% power so I'm going to rig up a pot so I have the option of variable speed.

I did some tests with my shitty little digital thermometer and ran the 360 slim for an hour without the fan, getting 93.9F. When I turned the fan on, I ran it for 10 minutes and came back to it at 83.1F.

It works, but I just need to make some sort of case so that the air gets blown INTO the console rather than blowing right out the sides. For now I just used some electrical tape to seal up the edges where the fans meet the console, and it works better than nothing.

FYI, the fans are placed on the end of the xbox beside the DVD drive and the hard drive, blowing air past the DVD drive and HDD since those are the sources of all xbox-related issues I've had in the past (fat and slim alike).

My idea for the fan casing is going to be some plexiglas held together by some silicone caulk. Thinking about rigging up some LED's since I have just under 50mA of unused power coming from the adapter, but since nobody really sees my xbox except me I'll probably end up just leaving the LED's out and painting the case gloss black with chrome accents to match the console.