Hello gang!

So I'm wondering what if instead of multiprocessor main-boards under one OS, is there a way build a machine that has multiple main-boards stacked somehow into a case using a large single power supply and have it run off one single hard drive with one OS? I'm wondering if this is possible under Windows, Linux, or some other OS?

Only if you network them, and you can't physically connect a harddrive to two boards.
But I'm not a hardware guy so I don't really know, but it sounds silly.

Edit: I stand corrected.
Edit again: Guess I wasn't.

Think about it this way. One case 10 computers versus 10 computers in 10 cases with 10 separate power supplies. I think the former is a better alternative because it saves space, generates less heat (possibly), maybe cheaper to build since I wont need 500 dollars just for 10 cases.

Great article

The question is why you need'em under one O.S?
You can connect them using Ethernet(for example), network boot from a single HDD..
So generally, it's just a question of a case and a PSU..

Sorry, no. I'm just speaking of general knowledge. Yet, It is obviously not an issue, if you get a proper case and PSU, as I stated before.

Edit:
or actually they just don't explain the logic behind having a single HDD.

The logic of having single HDD, is to save money obviously.. Also effort in some cases. & network boot makes it possible.

If you're really going to do this, and don't want to have a HD plugged into each mobo, plug one into the master node, and setup DHCP/BootP+TFTP and network booting on the rest. Have all of the slave nodes setup to boot off of the nic, and they will automatically query your master node for an ip, grab a boot image off the master, and finish booting. With the right config inside the boot image, each machine can setup their root filesystem over NFS as well. It'd be best for performance if all the machines spoke Gigabit Ethernet, and you put in a real Gigabit Ethernet switch (No hubs). Good thing is a decent 8port GB switch is rather cheap these days, and most motherboards come with at least one built in GbE port.

I'm not worrying much about the PSU, although I wonder if there is one for many boards so I can just have a PSU that has something like 10 connectors and can power each board. I'm more worried about storage, not sure how or where I could find one that's prebuilt, besides having to buy a system with it. I guess going to a hardware place and buying specialty metal frames with holes would work. I'm also thinking of liquid cooling and getting a processor from the AMD Black edition for overclocking.

Power supplies barely manage to run a single over clocked cpu these days. AMD's Black editions are all generally 125w or higher (some are 140w), and thats at stock settings. Over clock it and it's likely to jump much higher. Good luck powering multiple overclocked systems with a single PSU.

In the end you're most likely going to have to modify a case and PSU yourself. You might be able to find ATX power cable splitters on ebay or something so you might not have to actually splice in more ATX power plugs yourself.

If I was going to work on a project like this, I'd probably try and find a psu from a disused Blade server box, or even just an old redundant power supply from some server.

Warning: If you wanna run just one of the mobos at some point, or at least restart one having the rest on, you might need to think again.

I'm thinking of keeping the main node running while having the option to power on machines as needed with increased resource need. That would be the most effective system.

Is there any way to switch the nodes off based on need?

What I'm thinking is that, if it was possible to boot a node board off the main node HDD with the other boards staying off, then there wouldn't be a problem with the PSU since the boards that are running only draw the required current. The problem I'm seeing is, how would it be possible to boot a single node if the main one is running already? I wonder if it would be possible to just have a bootable USB for each board? maybe that would work.

I think I will try making a cluster with a main node and another mobo, so two computers together and see how that would work.

I see, basically if one machine is off the the whole thing is off too. Yeah, I have to see how that would run first and see if someone has invented some kinda 3rd party PSU kit for it.