~misfit~ wrote:
Apollo wrote:
Matt Giwer wrote:

As to cost, you cannot be drawing more than the wattage of your
computers power supply, probably closer to half unless you have four
hard drives and peripherals drawing power.

200 Watts X 24 hours = 4.8 KW-HR X cost per kw-hr

Most new psu's are 75% efficient at best, older ones even worse, so a
200W psu, under full load, draws about 250W. I do agree that
consumption at full load with only 1 hd and a low power gpu is
probably around half or just over half of the stated consumption.

A Pentium 4 PrescHOT CPU alone will use well over half of the
abovementioned 200 watts, before you even consider the losses in the
PSU and mobo power-regulating circuitry before the power gets to the
CPU. Close to 150 watts for the CPU alone. Then you've got to get the
heat out of the case.


I agree about todays HOT cpu's consumption, but as Matt was talking about a
200W psu I was thinking PIII / Low-end athlon/duron systems. I have no
experience of recent Intel procs, but I don't think I'd put a PIV system
together using a 200W psu ;o)

It all depends on your CPU. A PrescHOT has a thermal dissapation of
about 103 watts so it's fair to assume that it's using at least that
amount plus a little more. Motherboard circuitry uses a fair few
watts (have you ever put your finger on the power FETs on a running
PC, or wondered why northbridges have heatsinks/fans?) as well. An
AMD XP Athlon 32-bit dissapates around 83 watts.

I'm curious now, any idea what my cpu would consume; mobile XP2400 35W @
1.35v standard vcore - set at 1.93v. There must be some correlation, it
can't be linear or it would only be around 50W and I wouldn't need my
wetware setup.

You can expect 5-10
watts consumption from CPU fans. These figures are for
non-overclocked machines. You mention the efficiency of PSU's but
then there is the efficiency of the on-board power regulating
circuitry as well (the aforementioned FETs) that supply the low
vcores in the range of
1.5v from 12v. Then there's the GPU. Ok, SETI-farm boxes wouldn't
have much in the way of graphics power usually. However my main
machine is only running a nVidia ti4200 and, even on idle (desktop)
with it's great big heatsink and fan, it runs at 53°C. That must take
a bit of power to get it to 53° despite the best cooling Leadtek
could devise. Even my SETI machines run a basic 8MB S3 AGP card and
the GPU on those, while not heat-sinked, gets quite hot to the touch.
I have good case cooling, another 25 watts or so. (I have nine fans
all-up in my main PC, *far* more than 25 watts worth). Even my
southbridge gets hot, I have fitted a passive heatsink to it as it
was uncomfortable to hold my finger on it. Then there's the HDD, the
RAM also uses power (I've heard a figure of 15-20 watts mentioned for
512MB). You'd also be running a modem or a NIC, at the very least
(even if it's on-board). They consume electricity too.

Taking into account the efficiency of the PSU and the mobo circuitry
I think that the 200 watts mentioned is a fair middle-ground
estimate, considering some people will be running PrescHOT's, using
more than 200w and some will be running Celerons or Pentium M's,
using less. All, if running SETI, will be using maximum CPU power all
the time. (If the servers are up g).

I'm lucky I guess, I still have 24wu left in my cache, but only because I've
been away for the weekend and don't like leaving them running when I'm not
here.

I wish I knew someone with one of those sockets that measure power
consumption, I'd definately borrow one for a while just to see what I'm
using, I wonder if any tool hire shops have them?

Thanks

--
Apollo