I have a few old motherboards and cpus lying around that I want to use for BOINC crunching, but since I do not have the money for running several power supplies at 2-300W, I wondered if it is possible to have one unit supply 3 or four computers (700-1300MHz CPU and one old HD per computer, as well as LAN card and graphics card, if not onboard).
Has anyone else tried this, or is it not possible? Can I get premade cables for it or should I make them myself?

Only if the one power supply is big enough to supply the power for all three machines -- probably possible if you get a 600w power supply and you're careful to select low power components.

I would think the power draw would go down a little, but not a whole lot.

I've got some servers that draw a total of 30w (yes, thirty watts), but the floating point performance is awful.

> I have a few old motherboards and cpus lying around that I want to use for
> BOINC crunching, but since I do not have the money for running several power
> supplies at 2-300W, I wondered if it is possible to have one unit supply 3 or
> four computers (700-1300MHz CPU and one old HD per computer, as well as LAN
> card and graphics card, if not onboard).
> Has anyone else tried this, or is it not possible? Can I get premade cables
> for it or should I make them myself?
>

Perhaps there is something I have misunderstood then - doesn't the power supply draw 300W continously (If it's a 300W unit ;-) ) whenever the computer is running, no matter how much hardware is installed? Or does it only run as many watts as are required by the hardware?

> I have a few old motherboards and cpus lying around that I want to use for
> BOINC crunching, but since I do not have the money for running several power
> supplies at 2-300W, I wondered if it is possible to have one unit supply 3 or
> four computers (700-1300MHz CPU and one old HD per computer, as well as LAN
> card and graphics card, if not onboard).
> Has anyone else tried this, or is it not possible? Can I get premade cables
> for it or should I make them myself?

I would not recommend this especialy with ATX system and especialy if you
don't have any electronics knowledge. It wouldn't reduce your power conso
much anyway. The total system loads will be the same, the only economy will
be that you would have only one "working and joule efffect" loss by using one PS.

A power supply will always consume energy even without loads. But the power
it will deliver depends on what the loads require. In your case your PS would
have to deliver the power required by 3 motherboard. So basicly the results
would be about the same.

I would strongly recommend you to buy PS for each motherboard. You can have
300W PS for as low as 15-20 USD.

Friendly
Marc
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Thanks for your help! I already have a few power supplies lying around too, however they are not ATX - will they work with an ATX motherboard nonetheless?

> Thanks for your help! I already have a few power supplies lying around too,
> however they are not ATX - will they work with an ATX motherboard nonetheless?
>

NO

Some power supplies in AT boxes did come with both AT and ATX hookups, so those would of course work.

> Perhaps there is something I have misunderstood then - doesn't the power
> supply draw 300W continously (If it's a 300W unit ;-) ) whenever the computer
> is running, no matter how much hardware is installed? Or does it only run as
> many watts as are required by the hardware?

It's really helpful to have one of these: wattmeter

A 300 watt power supply can deliver 300 watts of power.

It only draws what it needs to meet the demand.

I have ten computers running in my server farm. Most have 300 or 400 watt power supplies. The total draw (ten servers, a couple of hubs, a few modems, CSU/DSU, etc.) is 580 watts.

I will try and get a watt meter and a few ATX power supplies then, and see if I can get a few more computers crunching. Again, thanks for your help everyone.

By the way, what is the best Linux system for running BOINC?

I don't work for Smarthome or anyone involved with the meter, but I have one of them and it works very well.

Among other things, I plugged our old refrigerator into it and measured the power usage -- and compared that to the new models.

We promptly bought a new one -- the payback was less than a year.

> I will try and get a watt meter and a few ATX power supplies then, and see if
> I can get a few more computers crunching. Again, thanks for your help
> everyone.

> I don't work for Smarthome or anyone involved with the meter, but I have one
> of them and it works very well.

That doesn't matter, as I live in Denmark (Europe) and most likely can't get that brand here anyway ;-)
But I remember our Electricity Company lending some out a few months ago, I'll try and get one of those.