Which uses more electricity. Desktop computer or laptop??

[Mark]

Originally Posted by SidewinderINC

My laptop PSU is 85W

My PC's PSU is 850W

I think that's my answer

It's also wrong. If you tried to actually use 850W, your PSU would either turn off (if it's a good one), or just plain die (if it's a Qtek ).

Originally Posted by leowyatt

laptop without a doubt.

Only 95% true. The micro PCs (Mac Mini, the really small Dell stuff, etc.) might beat a laptop, but only when the connected monitor is switched off.

If anyone has seen the macbook adverts it says that uses something like 1/4 of the power of a light bulb

Which is, to put it bluntly, BS. To do that, they'd have had to run it idle, with the screen off, and probably no battery. They'll also be comparing against soon to be illegal to sell incandescent lighting - put it up against an energy saver and it's game over.

Originally Posted by Haly

As my laptop spends half the day running on the battery, I assume it must save a fair bit compared to when I left the PC running all day.

Yup, but more than it would if you left it plugged in (with similar energy saving settings). When you plug your laptop back in, some energy gets wasted making the battery hot.

[Haly]

Originally Posted by Mark

Yup, but more than it would if you left it plugged in (with similar energy saving settings). When you plug your laptop back in, some energy gets wasted making the battery hot.

So if I left the laptop plugged in 24/7 it'd use less power than if I only had it plugged in for 4hrs a day? Or has one of us got the wrong end of the stick as I don't really get your logic?

[Mark]

You said it spends half the day running on the battery. That battery has to be recharged, so yeah, it'll use more than if you spent the same time on it but didn't use the battery at all (providing it has the same energy saving settings which rarely happens in practice).

[SidewinderINC]

Originally Posted by semi-pro waster

It's not quite fair to imply that the PC uses 850w though, you're absolutely right that the laptop will be far lower in power consumption terms but the PC will still only draw from the wall what it needs regardless of whether you've got a 300w PSU or a 1.3kw PSU (assuming in both cases that the systems nominal load is covered by the 300w).

Short answer is that the laptop will use less power, usually a lot less but the difference might not be hugely noticeable on power bills. You might also have to factor in time taken to do tasks depending on your uses - suppose for a second you're doing a 3D render and it takes 10 minutes on your desktop which uses 300w but 35 minutes on your laptop which uses 85w, suddenly it is a whole lot less clear-cut which is the best overall (nb I haven't worked out the figures, it's just an example).

Oh of course, but I tried to run the system on a 400W PSU and it wouldn't go so I know it's drawing more than that.

My comment was more that the laptop can ONLY draw up to 85W wheras the PC will use a lot more most of the time.

[Mark]

Originally Posted by SidewinderINC

Oh of course, but I tried to run the system on a 400W PSU and it wouldn't go so I know it's drawing more than that.

Probably not actually, unless it's SLI/Crossfire or heavily overclocked.

[divine]

Average 'high' spec PC will draw about 300-350W from the wall under heavy load.

Big PSUs are for a) peak draw headroom b) the ability to operate in better efficiency zones