Atomic I/O letters column #80
Originally published in Atomic: Maximum Power Computing Last modified 16-Jan-2015.Wasted watts
I'm curious as to the energy efficiency of a typical PC. How much of the power that goes in actually does "useful" stuff like pushing electrons around?
It seems to me that PCs are very inefficient - most of the power being wasted as heat. Say the PSU is 300W and it's fully loaded. Where's the 300 watts going? Some gets converted to kinetic energy (spinning HDDs, CD, fans, maybe sound waves if inbuilt speakers), some to light (the odd blinking LED). Practically nothing comes out in terms of electrical power (assuming no USB powered devices), as the only external connections (video, sound) only output milliamps if that. So I figure 80 or 90% of the 300W must be wasted in heat.
(Just think about all the things in a PC that have heat sinks - CPU, GPU, chipset, RAM, some HDDs, PSU. How long before we see a mouse with a heat sink?)
If you wanted to build a "green" PC, what would be the most energy efficient design? Presumably a notebook type CPU/GPU?
Adam
And the power consumption gold medal goes to...
Answer:
Well, elementary thermodynamics
tells us that all of the power that goes into any device will end up as heat.
Yeah, that's entropy,
man.
The question you're really asking, of course, is how much of the input power doesn't do anything useful on its way to heating up your computer room. The heat sinks on chips are there partly to get rid of power that hasn't managed to do anything useful, but they're mainly there to get rid of power that has achieved something, and is now following the inescapable thermodynamic path to equilibrium.
("Waste" heat can still be useful, if you're paying to heat your house anyway. If you're paying to cool the building, though, waste heat is doubly bad.)
There are some household devices that really do waste considerably more power than they profitably use. Ordinary ceiling fans, for instance. They have horribly inefficient (though very long-lived and easy to speed-control) shaded-pole motors, and their flat blades don't move air very well either.
Most computer gear has a pretty good ratio of watts-consumed to instructions-per-second, though, and the ratio is getting better with each generation of CPU. A 66MHz 80486 only consumed a maximum of about seven watts; a Core 2 Duo working flat out may need ten times as much power. But the Core 2 may easily be doing two hundred times as much work.
You can improve overall computer power efficiency by choosing components to avoid the ones with worse watts-to-work ratios - so a GeForce 8800GTS is preferable to an 8800GTX, for instance. You can also take advantage of the power saving features all modern CPUs have (I talk about that in this Ask Dan, where I also talk about laptop chips in desktop PCs).
For a given hardware and software configuration, though, the most important power consumption factor is the efficiency of the power supply.
That, generally, isn't great, though it's much better than you fear. The worst PC PSU ever made only wastes about four-tenths of the power it sucks out of the wall.
It's hard to pin down exactly how good, or bad, a given PSU will be in a given PC, because PSU efficiency varies with load. "80 PLUS" certification guarantees at least 80% efficiency at 20%, 50% and 100% of a PSU's rated load; a really good PSU these days should be able to manage about 85% in normal use.
In that situation, a computer that needs 300 watts to operate will be drawing 353 watts from the wall.
A cheap PSU may have efficiency as bad as 60%. If it manages a less-terrible 70%, then a 300-watt load will require 429 watts from the wall.
Realistically, someone with a pretty hot gaming PC and an ordinary PSU can expect to save only around twenty watts by switching to a high efficiency power supply. It's possible to do considerably better, but you probably won't.
It'll take quite a while for a 20 - or even 40 - watt saving to add up to the price of a new PSU. You can save just as much power by turning off at the wall a few appliances (including PCs) that draw several watts when they're in "standby" mode.
If you're buying a new PC, though, it's definitely worth spending a few more bucks to get a more efficient power supply. All things being equal, an "80 PLUS" PSU also ought to last longer than a cheap unit with the same rating. And that rating is less likely to be a complete lie, too.
It can't be pr0n if he only wants the first five minutes
My cousin overseas uploaded a video for me to download a family reunion and it was so large, approx 230Mb, that he RAR'd it into three parts and uploaded it to RapidShare. I hate Rapidshare but I downloaded all three parts anyway.
The first part opens up all right, but the other two give me an "archive is corrupted" error. My cousin said forget about most of the movie because it's only the first fire minutes or so that I'm after, and that should be in the first archive.
Can I extract the first part without having to mess around with the other parts because my cousin couldn't be bothered re-doing the movie so that all three parts work? I have got the first archive file in perfect condition sitting on my desktop.
Huccie
Answer:
There's no technical barrier to extracting incomplete archives in several formats, even
if you've only got enough data for part of a file. That means the file will be corrupt,
of course, but if it's a video format like MPEG you'll still be able to play it until
it runs out of bits.
Some archiving programs don't let you do this, but others do. WinRAR, for instance, has a simple "Keep Broken Files" checkbox in its "Extraction path and options" dialog.
Windows 2.0 also a problem
One might think that owning a laptop these days gives you the right to do with it whatever you see fit. It seems that Sony disagree. With USB floppy drive and SATA drivers in hand, we installed an XP partition on a brand new Sony Vaio VGN-FZ15.
Much to our dismay, there are no XP drivers available on Sony's site, and a quick call to Sony revealed that they no longer support Windows XP at all.
Being quite industrious, we set about looking for our own drivers. A few hours later we came to the conclusion that such a quest was pointless. Even station-drivers.com (a well known source of WHQL and beta laptop video card drivers) didn't seem to have drivers for the 8400GT under the hood of this shiny new laptop.
We couldn't even find detailed specifications about what is actually in it. So here I am, sitting in XP with no LAN, video, wireless or sound drivers. Touchpad works, though!
Alex
Answer:
No, it's not unreasonable to expect that you'll be able to run WinXP (or Linux, for
that matter) on a new laptop.
But yes, if the standard drivers don't work, you're screwed.
(It's been half a year now since this column appeared in Atomic magazine; perhaps the standard Nvidia WinXP drivers do now support 8400 cards. There's certainly no technical reason why they shouldn't; this whole problem is basically just market-segmentation bulldust.)
If your new computer comes with Vista on it, and especially if it comes with significant amounts of brand new tech, it's still a good idea to first make sure that you can get drivers for an older OS if that's what you intend to run.
Had you checked this before buying, you would have discovered that there are, as you've now found out, as yet no WinXP drivers for major components of some recent Sonys. It's quite possible that there will never be XP drivers for some of the hardware. The same applies to computers, especially laptops, from other big brands.
(After this page went up, a reader pointed out Sony's SOOPER SEKRIT WinXP downgrade driver page for recent hardware, which includes entries for the VGN-FZ1 series laptops.)
If you can't get drivers, but don't need to run very demanding applications under WinXP, then you could try setting up a virtualisation package like Microsoft Virtual PC (free!), which will run within Vista and present virtual "hardware" to a WinXP install that it'll be able to handle.
This is no good for big applications or 3D games, though.
(After this page went up, another reader suggested LaptopVideo2Go, a site which provides modified INF files to allow stock drivers to work with mobile graphics chips. There is indeed no technical reason why standard drivers shouldn't work; the INF files that come with those drivers just don't have entries for the mobile versions of the cards.)
DFI DeadConductor™ technology!
I have a DFI LanParty UT RDX200 CF-DR, which comes with onboard Karajan Audio. I also have an older Creative Soundblaster Audigy 2 ZS card, which was in my old PC, but hasn't made it across with the last upgrade.
I know that usually onboard sound is crap (read Realtek), but which is better in this case? My PC is due to be replaced once the quad core and DirectX 10 hardware settles down, at which point I will get a X-Fi or whatever is current.
In the meantime, is it worth putting in the Audigy 2 ZS?
Fraser
Answer:
Congratulations! You've got Realtek audio anyway!
DFI's "Karajan" module is (as you know) a little separate plug-in daughter board containing the motherboard audio hardware, which stands perpendicular to the motherboard next to the audio sockets. In theory the separate board might give better isolation or a smoother power supply or something; in practice, I doubt you'll be able to detect a difference.
The top-end Karajan modules, like yours, are based around a Realtek ALC885 or ALC882 (the ALC885's also used on the newer "Bernstein" module; budget Karajans have the slower ALC850), which is a very full-featured audio chip that provides a moderate amount of hardware acceleration for multichannel game audio.
The Audigy supports fancier EAX positional audio and effects modes, though, and ought to use even less CPU time in games, provided of course that it and its dodgy Creative drivers behave themselves on your system.
Both the ALC88x chips and the Audigy 2 are also "High Definition Audio"-compliant, able to play back up to eight channels of much-better-than-CD-quality audio. Which would be great if you actually have any applications that'll try to do that, which I bet you don't. I think you still can't get audio at a high enough bit rate from anything but DVD Audio discs for HD Audio to matter.
For every normal PC audio task except multichannel and/or positional game audio, your onboard Realtek audio (let's call it what it is) is perfectly fine. Cheap base-level Realtek chips may not have a terribly good reputation, but that's mainly because of motherboard design that gives a lousy final signal-to-noise ratio, or old drivers. The recent Realtek drivers have been very good.
If you want to use fancy EAX positional/environmental audio stuff in 3D games, then the Audigy 2 card can do stuff the Realtek chip can't, and will also give you a slightly higher frame rate, by offloading more processing from the CPU.
Otherwise, I'd stick with the onboard module if I were you.
