You've got, what, one DVD drive on the front of your computer? You have so many empty drive bays—how embarrassing! Here are a few awesome (and absurd) things you can put in those bays to add extra features to your computer.
The Useful Options
Whether you've built your own computer or you've bought one, you should be able to open those 5.25" and 3.5" drive bays right up and stick something in there. If you don't have any need for 3 DVD drives, though, there are a slew of other really useful accessories made to fit in there. Our five favorites include:
A Fan Controller and/or Temperature Monitor
I don't know about you, but my desktop is loud. It sounds like a wind tunnel in my office, all the time. We've talked about how to control your computer's fan speeds before, and if you have more than a few fans, software options won't cut it—you need some knobs you can turn down when you want your PC to stay quiet. Luckily, most external fan controllers are built to fit right into those 5.25" drive bays. You can get something simple like this four-knob controller from Scythe, this slider-based controller if knobs aren't your thing, or even one with a fancy LCD screen. These are especially cool because they can not only monitor and show you the temperature of your computer on the screen, but even adjust your fan speeds accordingly.
A Drawer for All Your Odds and Ends
Your desk may have a lot of drawers, but some of your more important accessories—flash drives, USB cables, and the like—probably get lost in all the chaos. If that sounds like you, consider getting a 5.25" drawer like this one from Cosmos that fits right into your front drive bay. It may not be as flashy as some of the other items on this list, but it's practical as heck, and almost certainly better than leaving the bay unused. You could even rip out the plastic sleeves from a cheap CD case and keep all your installation discs and other CDs in there, if you can't think of what to do with it.
An SD Card Reader and/or Super Fast USB 3.0
Most laptops these days come with SD card readers, but few pre-built desktops—and even fewer custom-built desktops—are lucky enough to have them built-in. And, if you take a lot of photos, you know how annoying this can be. You can add a simple SD card reader like this one to your machine for cheap, or, for a bit more money, grab one with built-in audio jacks, two fan controlling knobs, and extra USB ports for the front of your computer. What's especially cool is that many of these have USB 3.0 on them, which is great if your case doesn't have USB 3.0 ports in the front. As long as your motherboard has a USB 3.0 expansion socket, you can get those blue ports on the front of your machine and enjoy blazing fast USB speeds. Or, if you're still using USB 2.0 devices, at least enjoy a bit of increased reliability.
A Hot Swap Drive Bay for Extra Hard Drives
A hot swap bay, like this one from Silverstone or this one from Thermaltake, puts a tiny door on the front of your case in which you can slide in a bare hard drive and connect it to your computer. Need to clone your drive, but don't want to open up your entire machine to hook up a new hard drive? Throw it in the hot swap bay. Troubleshooting a friend's hard drive for problems, but can't use their computer? Throw it in your hot swap bay. As soon as you slide it in, it'll show up on your computer just like an external drive would, and you can work with it immediately—no need to rummage through your computer's innards or find an external drive enclosure. It's not something everyone needs, but it's easy to figure out whether you do. If you've opened up your computer in the past 3 months for some mundane hard-drive based task...this will change your life.
A Volume Knob and Remote Control Sensor
If you don't have your own dedicated home theater PC, you can still get in on some of the fun with a multimedia station for your desktop computer, like this one from Antec. It adds a volume knob to the front of your computer, as well as lets you control your music or videos from across the room with the included remote control. Whether you're kicking back in your office chair for a bit of TV watching or you're listening to music from across the room, it's the perfect upgrade for media lovers sick of using a keyboard and mouse for everything.
These aren't the only useful options for those drive bays, of course. We stumbled upon some other cool things like hard drive fans (perfect if your case is a little low on cooling) or adapter brackets for mounting more internal hard drives. Heck, one Redditor even silenced a really loud drive by mounting it in a 5.25" bay with rubber bands (which is super clever, but I'm not sure I'd want to risk the rubber bands breaking). If you're still looking for useful ideas, browse around computer stores like Newegg, or check out this handy page at FrozenCPU. There are a lot of inexpensive, useful upgrades you can make with those empty drive bays.
The Ridiculous Options
In my research for the above upgrades, I found a lot of weird, unsafe, and just plain absurd things designed to fill the drive bays on a desktop PC. I couldn't leave without including them, so here they are, for your viewing pleasure. Thankfully, these are all out of stock (or, in one case, a joke product), so even if you think its a good idea, you'll be forced to forego them in favor of something a bit more useful.
A Cup Holder Plus Cigarette Lighter
I don't know who thought this was a good idea, but once upon a time, apparently you could buy a 5.25" bay with not only a cupholder, but a cigarette lighter in tow—and all for the low price of $5.95. Thankfully, it's been discontinued, so you aren't tempted by the convenience of such an absurd (and kind of dangerous product).
I'm sure you could DIY the cupholder portion together, but...why would you? Keep that liquid away from your machine! If you're really keen on the idea, though, you could always grab a USB mini fridge instead. It's safer, and even more ridiculous than a cupholder. Jackpot!
A Tiny, Second Monitor
Okay, so this one isn't quite as ridiculous as the others—I could see it being kind of cool—but it's still hard to look at without laughing. Apparently, Thermaltake used to make a 7-inch LCD screen that would mount right on the front of your computer. I imagine it could be useful for keeping an eye on BitTorrent downloads or having a little terminal window open at all times, but at 7 inches, you're probably not saving a ton of space on your regular monitor—and at $100, you might as well just buy a second, full-size monitor instead.
All that said, if you like the idea, a pretty big modding community has popped up creating DIY versions of this for different computer cases, using the screen from the mobile PSOne. Here's one of the better how-tos if you want to see what it entails. It's pretty intense, but the final result looks pretty good for a DIY project. But again—you're probably better off just buying a second monitor, unless your office is seriously cramped for space.
A Toaster (or an Easy Bake Oven)
The final, and easily most ridiculous thing I came across when researching these accessories, was a toaster that fits in a 5.25" drive bay and pops toast out sideways...that came with software that let you tweak the toasting time and heat levels. After lots of skepticism, I discovered that it was, in fact, just an April Fool's prank from CrazyPC.com. And thank God, because this sounds like the fastest way to destroy your PC's innards I've ever heard of (not to mention get some weird-tasting toast. ThinkGeek had a similar prank with a 5.25" Easy Bake Oven, for the gullible folks that preferred sweets to toast.
So there you have it. If the front of your computer's looking a little bare and boring, you might get a lot of use from these handy accessories. And, if not, at least you got to envision the idea of making toast underneath your optical drive. Have any other great (or absurd) ideas for your computer's external drive bays? Let us know what you're using them for in the comments.
If your computer's running a little loud for your tastes, it's probably because your fans are running at full speed—even if they don't need to be. Here are a few ways to manage your fan's speed so they're keeping your computer cool when they're necessary and silent when they're not. 
The most ideal way to control your fans is with something like 
Many motherboards have fan control built-in to the BIOS settings these days, though they don't always give you as much control as something like SpeedFan does. But, if your computer isn't supported by SpeedFan, this is a good plan B. Open up your motherboard's BIOS settings (usually by holding a key like Delete when you boot your computer), and search for the fan settings. They're called all sorts of different things (for example, Asus has "Q-Fan Control", while Gigabyte has "Smart Fan Control"), but generally you should be able to find it under one of the BIOS menus. Enable this feature, and tweak any settings it gives you to your liking. Some machines may only let you set it to conservative or liberal mode, while others will let you individually set temperature thresholds like SpeedFan.
While the above methods are great for automatic fan control, they aren't always available on every motherboard—and they'll usually only control one or two fans in your rig. If you want control over everything, you can install an inexpensive fan controller like 
Frugality blogger Mr. Money Mustache recommends adding thermal mass to your home to cut down on your heating and cooling bills. By his calculation adding around 15,000 lbs of thermal mass through normal DIY projects (replacing carpet with hardwood and tile flooring, adding concrete countertops) saves 2.5 hours of running his central air each day. 
Need more motivation to check out your air conditioner and properly insulate it? In New York City, the costs of fuel lost through gaps around air conditioners is sometimes as much as the cost of the building's entire cooling bill.
