I have a PC set up in a cupboard which serves my audio needs via various speakers around the house. At the moment I turn it off at night since I only use it for a few hours each evening. This gets tedious turning it on and off and I`m wondering how much extra its likely to cost me leaving the box on 24/7. We have economy 7 that switches in at 1am, so overnight I would assume it would be a lot cheeper. The box itself has a 250W PSU and is AMD driven with 1 CDRom drive and 2 hard disks, sound card, graphic card. I do have a monitor connected which goes into standby after a few minutes, but I would probably turn this off as it does produce some heat.
You don't say what speed the processor is - this makes a big difference. Total consumpsion of the PC with the monitor off is going to be 100-200W depending on the CPU.
Let's assume 100W. At normal prices a kWhour is ~6p, at Economy7 I think it drops to ~3p. I have no idea how long your Economy7 period lasts - say 6 hours?
So say you run for 18 hours at normal rate, and 6 hours at reduced rate. That's (18x0.1x6) + (6x0.1x3) = 12.6 pence per day. About £4/month, or £45/year, or £450/10 years.
Might be an idea to also run "Rain" or similar which will lower the cpu consumption when idle. Consider suspend to ram or hibernate as options as well, if you don't mind the delay and have a suitable method to bring the machine of of standby/hibernate. Not so much for the power consumption, but the heat/noise of leaving the thing on 24/7, though I suppose the cupboard will muffle most of the noise anyway...
I physically disconnected the PSU fan when I ran my machine like this. It was a 33MHz 486, which was easily enough for the task. It was running Linux, with the hard disks set to shutdown after 10 minutes and logging disabled, so it wouldn't need to write out the files. It ran like this for a couple of years without any problems whatsoever.
A modern machine might have more difficulty without the PSU fan. I used the old 33MHz motherboard (even though I had a 300MHz AMD available) because the
33MHz processor required no CPU fan. When you aren't running graphical applications, modern processors are simply not needed.
Reasonable guesstimate, ass-U-me'ing the OS and motherboard don't go in for deep power saving, is that you might be eating about 150W when you're "not doing much": your CPU will eat say 50-60W, the drives are spinning but not doing much else so just a few watts each, your PCI cards and memory modules won't be pulling more than a few watts each, and you have a few fans on the go. Call it 100W of consumption on the DC side, pretend your switched-mode PSU needs 120W of mains to supply that 100W, pretend your monitor in standby eats 20W, add 10W to keep Mr Maxwell and his thermodynamic demons happy, to arrive at the 150W handwave. That's one kWh every 7 hours (rounding off), so call it 3kWh for the 21 "unused" hours in each 24h period. Let's say one of those kWh's coincides nicely with your 2p-a-unit E7 tarrif, and that you're charged 8p a unit for the non-E7 units (typical 'leccy company E7 tarrif bumps the price up a tad for the non-cheap period); call it 18p or 20p a day for this "unused" power, or about 60-70 quid a year. Not peanuts, not massive, and in winter the extra bit of heat is something your central heating might otherwise be providing (at a cost more like 2 or 3 pence per kWh than the 6p-average you pay for leccy).
You may find you can persuade the motherboard, BIOS, and OS to do either deep power-saving or timed-on/timed-off for you; if Windows, fiddle around in the Power Options control panel; if Linux, apmd or (if you're ready for the bleeding edge) the acpi patches. You may find hibernation a useful thing to decrease the boot-up time. You may end up with a combination of methods - for example, using some freeware/shareware thing to do the shutdown, and using the motherboard's wake-up-at-given-time feature to start up. There's an eternal argument about whether machines last longer powered up 24x7 or turned on and off as needed; I'd suggest that in your case there's not a massive amount in it, with save-the-planet concerns tipping the balance towards non-constant running.
Never mind the operational cost, but you could feasibly buy a timer which plugs into the socket which turns the mains on and off at the appropriate time intervals.
Powering up shouldn't be a problem - the PC should boot normally.
Powering down is a seperate requirement though - you should close the operating system down before switching off the power. You can get a cheap shareware program to power down the PC and if you set that to happen say 15 minutes before the power went off then you'd be laughing.
Overall cost likely to be less than 50 quid for the above - which is very roughly what you might pay in a year for leaving the PC on 24x7.
Not always a good idea to have the HDD spinning up and down. It will damage the bearing and could cause one of the heads to clash with the disk surface, ruining large parts (if not all) of the drive.
My own experience was a total loss on a drive after 18 months with it set up as you say, but an identical disk bought and set up at the same time, is still running strong after 5 yrs in an always on mode.
Acquaintances of mine have had total failure after 18 months to 3 yrs, spinning up and down. These have each occurred with different makes, btw.
Assuming you're running something silly like windows
formatting link
cron and shutdown, then you can just cron a shutdown whenever you want, if you also stuck a network card in and wake on lan, you wouldn't even need the timer to do anything - just poke it with the lan when you want to wake the thing up.
If you fit something like Vantec Stealth fans, there is not that much noise to worry about, particularly if you have themostatic fan control too. My machine has five case fans, two PSU fans and four fans on various chips, but is hardly noticable at half a metre.
No, hasn't done for ever-such-a-long-time; and possibly the marketing name Economy 7 may have always meant "one set of wiring, two prices depending on time-of-day". The use of separate wiring for night-time loads was a feature of (some) storage heater installations, when the leccy boards and Dimplex still thought heating up bricks with overnight TooCheapToMeterYeahRightSellafieldWindscale leccy was a smart idea for wide use...
Stefek, glad his kernel rebuild has just finished and he can get back to work-or-near-offer...
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