Slashdot Mirror

← Back to Stories (view on slashdot.org)

'Case-less' Rackmounts and Multi-Machine Power Supplies?

Posted by Cliff on from the things-you-keep-in-a-computer-room dept.

phungus asks: "I'm looking for manufacturers of rack-mounted 'case-less' system trays for a project I'm researching. I'd like to rack-mount all of our dedicated servers without using cases. Ideally, you could put all of the components on one tray. I'd also like to find out if anyone knows of manufacturers who make big multiple-machine power supplies (ATX) so that I can eliminate individuals from the picture. I seem to recall an advertisement in a Linux magazine that did exactly this but can't seem to find it anymore. It would be nice if it supported standard relay racks, but full-enclosures would be okay too."

1 of 13 comments (clear)

  1. This is a bad idea waiting to happen... by stienman · · Score: 3
    There is no good reason to have a single, central power supply for multiple CPUs, but there are several bad reasons:

    Power supplies now are cheap and small, due to high demand. They are not any less efficient than a single supply would be (ie, a 70% efficient single supply would turn as much energy to heat as 20 70% efficient power supplies given the same load)

    Were one machine to fail, unless you have some sort of hot swap in place, you have to shut off all the machines on the power supply.

    A significant portion of your current at low voltages (3.3V, 5v, etc) are lost in the wiring from the power supply to the MB. Say your wiring is .01 ohm per foot, with 3 feet to the computer. 5V at 80A (8 MB) introduces a .8V drop across the copper, resulting in 64W being lost as heat, and the MB only getting 4.2V. (this is an exageration to show the point, were you to do this you'd have to make copper busses (say, 1/4" by 1/4" copper bar for each voltage) which would have lower resistance) Which is a main point in using high AC voltage for distribution: Higher voltage results in less losses for less copper and long distances. Don't make your power supply go for more than a few inches to your mobo unless you know what you're doing.

    There are numerous other reasons, but I'd say efficiency and fault tolerance are the two biggest reasons to avoid this idea. I'm assuming that since you're considering this idea you're rolling in money, as a custom power supply (which is what you're after) of this size is not trivial.

    -Adam

    Some minds are like cement: Thouroughly mixed and permanently set.