I'm new on cooling, and on one of my computers, I was thinking about putting one of those drive bay coolers with 2 fans that bring cool air in and takes out warm air. Is that designed to cool the whole system, or just like the CD and DVD drives? On my other system, all my drive bays are full, so I couldn't do this.

Also, this applies to both of my comps, I have a power supply fan that takes out warm air near the back, and was thinking of putting a case fan in the front that pushes cool air in, but I dont have an opening in the front of my computer to do that. Would the only option be to mod the case? Or how else is there for a case fan or any other options? Thanks

The 5.25 drive bay coolers I have seen are typically to draw air into the system to provide cool air. Personally, unless it directly hits a warm HDD or is between a couple of CDROM drives, I don't use them. (Personal preference) Hot air rises, so you would want to draw air out from the top, and draw into the bottom and the normal method is in from the bottom front and out through the top back. Basic rule tho is in through the front, out through the back\top. You want about as much out take as intake and vice versa. For example, if you have three 80mm outtake fans, I typically run three 80mm intake fans... Anyways, if there are no openings for an 80 mm intake, you may need to mod the case. Verify that the front bottom does not have a grated spot for an 80 mm. This is a typical spot to place one. If not, scope out a spot that has room for a fan. Many people will put them on the side cover that will draw cool air directly on the processor or the video card. I use a 3 inch hole drill saw to cut an 80mm fan hole. Be careful and if you can find someone that has done it before. Good luck
Bug

The hole saw is a good idea, but don't push it real hard or it may bind and mess up the hole or hurt you( it could happen.... maybe). Don't push down hard on it and hold the drill at a right angle and you should be fine.