Need 12v power supply for a cluster of 70 servers

The power requirements would depend on average current drawn on your boards. For example, our boards draw less than 1A @ 12V and a 50A auto charger would be enough to power 70 of our boards (500 MHz each). What are the rated power consumption of your boards.

Thanks for you reply. Here is the information I got from applet that is at:

I'm assuming a p4 motherboard running at 3GHz, with two hard drives and two 40mm fans doing heavy processing.

Totals 3.3V 5V 5V SB 12V Total (watts) Total Amps Current (A) 3.61 3.37 0.06 8.04 125. 10.4 Power (W) 12.1 17.0 0.29 96.1

So in the worst case. I'm guessing 10.4*70 = 725 amps

VJ

Hilarious. I wonder, at what stage of the design, they discovered that their connector could only be installed in the 'unreachable latch' position.

.....and why they didn't bother to fix it........

RL

Why two hard drives (10 to 15W each)? Can you live with just one or none (via file sharings)? Heating and Cooling this 10KW OVEN is going to be a problem, not to mention your electric bills. Do you run them continuously or just once in a while? If on all the time, you might save more money with laptop motherboards and P4 mobile. Laptop components generally use less energy and they are more expensive for that reason.

Perhaps the most common orientation of the mating connector on motherboards was the reason. You don't want to the piggy back board to stick out. Ah, they have an ATX extension cable too, in case it doesn't fit in the planned way.

I'm unclear, what is the purpose of your dc-dc picosupply?

If by cheap you mean cheap, maybe get a pile of scrap machines and common all the 5v outputs via Rs dropping say 0.15v. Ditto 12v. Cost nada.

Or if you're feeling real crazy, run 12 boards in series on rectified mains, and use wireless cards to provide isolation. Its a joke, dont consider it!.

NT

It's usually a POOR idea to use some unique, single-sourced solution. Most of these companies go belly-up within a year, then where are you?

Also from the picture it looks like they have this big graham-cracker sized PC board hanging on the ATX connector. Most motherboards don't have enough clearance to accept that. So you have to use an ATX extender cord. You've just doubled the number and trouble from sliding contacts (and cheep, tin-plated ones at at that).

And it's a bit ridiculous chopping up 12 volts to supply 5 volts to the motherboard, which in turn is going to chop that up down to 3.3 volts or less.

I'd use one biggish ATX power supply for each 2, 3, or 4 motherboards. Better yet, measure tha actual current draws on the +12 and +5 buses and bunch up the motherboards so each power supply is running at 75% of capacity.

Two hardrives so that I can do hardware raid. That in itself is not critical I can do with one hard drive. I'll also consider going diskless and add extra memory instead.

Pentium M is not an option because the motherboards that support it are few and it costs a lot more. The servers will be crunching data most of the time and the rack will be up most of the time.

I'm located in a business incubator so power bills should not be a problem for the next 12 months :->

Definitely to consider that. Perhaps linking with 100M or 1G ethernet.

You can custom made and stock up on boards. They are cheaper than custom power systems.

But coolings and wirings would be a problem. Take a look at the auto battery jumper cable. That's the type of cable you need for 100 Amp. I can't think of anything for 700 Amp.

That's not a bad idea. I was looking at 300 watt 1u power supply which could easily power two of the boards. The problem was that there are no atx connector splitters that I could find. Someone else had the same idea:

Took him about an hour to build the y cable.

It took me an hour on google to find this:

The only downside I see is that you would have to bring both motherboards up and down and the same time. Which in itself is not a big problem.

I guess the pico psu with once central dc is not the way to go. See my other post at the bottom which takes one cheap ATX PS and feeds two motherboards. I'll also look into having most of the servers run diskless.

Is there any potenital problem of having one power supply feed tow motherboards?

Actually, it's more ridiculous then that. When the big I* designed the ATX PS, they decided to use 3.3V for the core. Guess what happened to the

So, in this case, you have 12V to 12V DC-DC regulated to 1.2V.

Most of the switching regulators are designed for 9V to 12V. You can't use 5V. They are LDO (low drop out) linear regulators. If you are serious about this project, you should spent more time designing your switching regulators.

With compute density also goes power density, and thus also heating and cooling costs as well as direct energy expense.

at 200 amps and above busbars are often used. at 400 A and above busbars on the order of 1/4 inch thick and 2 inches (or more) wide are used.