PC case necessary for airflow? dust protection?

I’m thinking about building my own computer and wondering if the computer case is really necessary. Would I get an overheated, dusty mess if I just leave all the components out in the open?

I’m primarily concerned about heating. Would it matter that I don’t have a narrow stream of air flowing around the computer parts? Would having the CPU fan run in the open provide less cooling than if I had stuffed everything into a case?

Dust is the other issue. I was thinking of screwing in the motherboard and the drives to the underside of the shelf on the wall. Would it attract more dust that way or in a case?

I’ve heard about open-air PC cases, but I’d like to do away with the case altogether if I can get away with it.

It depends. A lot of off the shelf PCs are designed with undersized fans (to keep the costs down) and will overheat if you open the case up. On the other hand, I’ve built open machines onto plywood and they’ve worked fine. Dust will be an issue, and the CPU may need additional cooling since it won’t have ducted air blowing across it. In my experience, though, the CPU will usually be fine as long as you have a good heatsink and fan.

It used to be that you really only needed to worry about the CPU, but other things can overheat in a modern computer as well. Pay attention to the graphics card and the disk drives in particular. You may need to mount fans near those as well to keep them adequately cooled.

The case also protects the computer. If anything metal falls on your open air PC it will short things out and cause major damage. Even non-conductive things can damage circuit boards and other delicate parts.

you may get less cooling if out in the open compared to in the case. it’s an all depends on both situations. the forced cooling you will still need (any maybe more of it) will be noisier.

you will get lots of radio noise without a case; you may not be able to use a radio or video in the vicinity of the computer.

I have only built one computer and am not expert at this but I would think there might be grounding issues.

Keep it inside a case.

Cooling is one big reason for a case. The case will have fans to pull cool air into it, pass it over the CPU (and video boards) and exhaust hot air out of the case. Without a case, you don’t have that directed airflow – just fans blowing air around in the area. It won’t work as well.

Dust control is another good reason for a case. The fans bringing cooling air into the case have screens or filters in front of them, to catch dust and keep it from getting onto the components. If you build one with them all out in the open, they will attract dust.

There are also grounding issues (RF interference), as well as the physical protection of these expensive components. And how will you mount your hard drives safely & securely?

Also, you mention mounting the motherboard to the bottom of a shelf – do you mean upside down? Then where will the heat go? Motherboards are designed for typical mountings either rightside up or sideways in a tower case; I doubt that upside down mounting would work out well.

Just why do you want to “do away with the case altogether”? It’s only a minor part of the cost of a system.

You could always try cooling it with mineral oil. :slight_smile:

Yes it’s possible to do without the case. It’s not a good idea and the savings are minimal considering a case is one of the least cost prohibitive components. Those circuit boards need to be held somehow why not use the device made to do it.

Yes, you need a case. Dust will lead to dusty which will lead to overheating. Plus good cases have fans that will cool better than exposed components.

Find a nice case.

In addition to directing cooling, and keeping out dust, a case:

Prevents damage to the compontents
Prevents damage to fingers being stuck into the fans. (I’ve done it, and it hurts.)
Reduces noise (fans can be loud)
Supports the I/O jacks and the on/off and reset buttons. (You will still need to mount and support USB, video, sound, and network jacks someplace.)

It can be done, but it’s not going to be as easy as just screwing the motherboard onto the bottom of shelf.

WARNING: DIY GEEKAGE ALERT

There’s a caveat here - most cases are set up by default to provide “negative pressure”, that is, the exhaust fans (including the PSU fan) push more air out than the intake fans draw in. With this setup, you will not be able to filter all dust out, and you will get dust in your system, even if the intakes are filtered, since the negative air pressure sucks air and dust in through all the openings in the case. And the fewer side/front/top vents you have, the more air gets sucked in through the I/O panel, where dust can clog USB ports and lead to shorts or other problems.

Whenever possible, I try to use “positive pressure”, where the air pressure generated by the intake fans is greater than that generated by exhaust fans. This forces air out of the openings in the case instead of pulling air in, and allows you to keep most of the dust out by filtering the intake fans. This does require better fan placement planning, since you can by nature, pos pressure creates poor airflow and you need direct cooling pointed at your critical components. Also note that since the PSU may act as an exhaust fan as well, you’ll need more intakes than you may think initially.

I have a system set up in a CoolerMaster 590 (awesome case, by the way), with 4 120mm fans pushing air in (2 placed at the top of the case, blowing on the CPU and NB chipset, one pushing air over the HDD, and one on the side panel blowing directly on the GPU), and a single 120 exhaust in the back. My PSU is isolated from the airflow, as it pulls its intake directly from the bottom of the case (filtered). Because intake fans are quieter than exhaust fans (all things being equal), this thing is whisper quiet - you have to look at it to tell that it’s on. And cooling performance (with a Pentium G840 and a GTX 460) has been stellar - rarely have I cracked 60C unless I’ve pegged the CPU for several hours. Could I pull lower temps with a more direct airflow? Possibly, but in the 18 months I’ve had this setup, I’ve never had to clean dust out of the system, and thus, haven’t had the corresponding drop in cooling effectiveness.
More germane to the OP (case or no case?) - before I looked into positive pressure setups, I was running a PC in negative pressure mode, in a pretty vanilla configuration of 1 intake and 2 exhaust fans. I was doing a lot of DVD and TV episode transcoding, and found that taking the side panel lowered temps a bit when the system was pegged at 100% 48 hours at a time while it churned through a Handbrake queue. So I ran it for several months with the panel off, while I ripped our DVD collection in fits and starts (and did normal stuff like games and web browsing in between).

When I put the panel back on after about four months, there had been hardly any dust in the system. When I cracked it again after a couple months to upgrade some components, the dust buildup was about double what it had been with the panel off. This is because negative pressure setups create a very distinct airflow, which routes the dust near all the critical components of the system and the extra dust sucked in through the other holes in the case gets pulled into the airflow and sticks to those components.

Cases are good. They keep stuff in place, and prevent your cat from pushing the computer off the table.

But others here are overplaying the need. I’ve had systems run for years totally exposed to the environment. Yes, they get more dusty, but a few squirts of compressed air every few weeks totally solves that problem. Overall, I’d say the dust problem is reduced, since it’s glaringly obvious when there’s dust buildup, as opposed to inside a case that you never open and you notice nothing amiss until it crashes due to the fan seizing up.

Modern components are quite resistant to electrostatic discharge, poor grounding, and other environmental factors, and I’ve never witnessed unreliability for those reasons.

The reduction in airflow is compensated by the fact that the air is cooler overall; case fans can only replace the internal air at so high a rate, and the ambient temperature is therefore higher. Not that it matters; modern components generally run fine even at 80-90 C.

So while I’d take the advice here to heart and consider the downsides, I also don’t see anything critically wrong with your proposal.

Hang them on the wall:

https://picasaweb.google.com/Dragon43/NewComputer

https://picasaweb.google.com/Dragon43/March2011

Got a couple of years in doing this. 3 computers, 7 cats & I spill stuff all the time.

Every computer case that sits on the floor that I have opened in the last ten years in even the cleanest house is a dirt nightmare. Only a few obsessive geeks clean their computers frequently enough.

3 windows puters & a LINUX puter are up now.

You will note that each hard drive has it own fan suspended with rubber bands and the hard drives are sitting on rubber blocks.

I lay out the computer on a piece of 1/4" plywood & add the mounting points to work best for my constant messing with stuff, ease of connecting & disconnecting cables.

Connections to the mother board work better on the side than the bottom … Trust me on this. I mount the motherboards from 1/4 to 1/2 inch from the ply board for cooling.

If you house does not get hot, your computer will not get hot.

As said, you can see the dust & when it needs cleaning.

You can see fans that have stopped.

I have no interference problems but I do not have all the stuff some have around computers.

It can be done neater and a better varnish job on the wood is always possible.

I feel that surge protectors and battery back ups are much more important than cases.

I do not encourage systems on the under side or flat on horizontal surfaces… For all the reasons posted up thread.

Vertically works really well for me and so is what I do.

Components run hotter & hotter with each advance in tech. & I have not had a problem with this setup.

YMMV

I can do more detail pictures if anyone does not understand what I am doing here. My rig is always changing as I keep messing with stuff.

I should clarify - when I say that I’ve had my setup for 18 months, I mean the case and fan setup. I just recently upgraded to the Pentium stuff in the same case.

Of course it’s possible to go without a case, it’s just a terrible idea (for reasons other posters have already mentioned).