Wikipedia:Reference desk/Archives/Computing/2014 December 15

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December 15

Pc issue

hi.i have problem with my PC.My PC turn ON when i switch on the power at the power outlet. Already try some Basic troubleshooting steps but the problem still there.219.94.83.162 (talk) 01:07, 15 December 2014 (UTC)

If you shut it down from the Start button, does it stay off? If not, it may be something simple like your power button being stuck down or plugged into the wrong connector on the motherboard. Alternatively, your BIOS may be set to "Power on after power failure" - see, for example, this article from RS. Check your BIOS and see if this option is enabled, and disable it if so. Tevildo (talk) 01:24, 15 December 2014 (UTC)

[Moved from talk page] THANK. ALREADY TRY IT.EVEN TKE OUT MOBO FROM THE CASE ALSO DISCONNECT ALL CONNECTION AECEPT PSU CORD.PROBLEM STILL PERSIST.219.94.83.162 (talk) 03:54, 15 December 2014 (UTC)

1. What operating system do you have? (Windows 7, Windows 8, XP?)

2. What happens when you click on Start > Shutdown? Does the PC shut down and restart? Does the power light go off?

3. What sort of motherboard do you have? We'll be able to check what BIOS settings are available if you let us know.

Tevildo (talk) 12:44, 15 December 2014 (UTC)

• The green wire of the PC is shortcut to ground
• the front panel power switch is locked in position "on"
• In the BIOS the "POWER STATE WHEN POWER LOST" setting is set in server mode "ALWAYS ON". Change this setting to "ALWAYS OFF" or "LAST STATE".

--Hans Haase (有问题吗) 19:39, 15 December 2014 (UTC)

can website block my ip address from accessing that website?

can website block my ip address from accessing that website? is that possible? Ram nareshji (talk) 07:39, 15 December 2014 (UTC)

Yes, that is a standard access control method. It can be done in the web server configuration or with a Firewall, etc. Why they would block it is another matter. You can sometimes get around such blocks with a proxy server or virtual private network. 70.36.142.116 (talk) 08:15, 15 December 2014 (UTC)

Yes, indeed, but there are other ways in which your IP address can be blocked other than by the website itself. Thincat (talk) 08:54, 15 December 2014 (UTC)

Even wikipedia does it. Vespine (talk) 22:17, 15 December 2014 (UTC)

videos on computer

Hi, I've sometimes watched videos on my computer, including those I've downloaded onto my hard drive, and they play up in the same way as a CD, with some kind of "track skipping". That is, it gets jerky, and replays the same bit a few times, then gets going again. Why would a computer file be prone to any kind of track skipping? Surely it isn't the hard drive physically playing up (for if it was, there would be so much more wrong with my computer, I would think)? So assuming it's software, the problem makes no sense to me - I would expect freezing, crashing, or entirely random behaviour. Mimicking a physical malfunction seems strange. Any explanations?? Thanks in advance, IBE (talk) 08:55, 15 December 2014 (UTC)

When you play a video there's various things that have to happen between the hard drive and the screen. Depending on your computer, the video file will be loaded chunk by chunk into RAM or video memory. As it plays, the file then has to be decoded by the CPU or by a video decoder on the graphics card to form the picture you see on your screen.

Any one of those steps could cause stuttering. If your hard drive is busy, it might not provide the next chunk of the file in time for it to be decoded. Insufficient memory could cause the same problem, as the computer has to move other things back onto the disk to make space to load the new file. Or, if the resolution of the video is too high, the computer might simply not have the graphics-processing power to decode the frames at the speed it's trying to display them. If you know any information about your computer (how old it is, the amount of RAM memory, the type of processor, whether it has a graphics card), that might help to identify which component could be acting as the bottleneck. —Noiratsi (talk) 10:11, 15 December 2014 (UTC)

As Noiratsi says above, the computer has lots to do, so I find that it sometimes helps to close down all other applications and processes that I don't need. This might include agressive anti-virus software -- mine seems to disobey my explicit instructions to run in the background, and sometimes takes over processing time from what I want the CPU to concentrate on. Dbfirs 21:40, 15 December 2014 (UTC)

Audio data is written into a circular buffer in RAM and the sound card reads from that. If new data is not written in—because the CPU or hard drive is overloaded, for example—the sound card will wrap around the buffer and play the same short segment of audio repeatedly. Video also typically uses a circular buffer of 2 or 3 frames, but the frames are advanced by the same software that's drawing them, not by the video hardware, so if no new data is available the video will normally just freeze. -- BenRG (talk) 22:08, 15 December 2014 (UTC)

Lowest possible signal strength?

I just found out my phone has a way to display signal strength as a figure rather than bars. I know this won't improve anything but it's fun to see. When I have no signal here it shows my signal strength between -109 and -113. What's the lowest it can go where I actually have a valid signal for voice calls? Also, what's the very lowest it can go, for example if I sat inside a lead lined box underground in North Scotland. It's a GSM phone if that matters. 81.138.15.171 (talk) 10:30, 15 December 2014 (UTC)

The unit is dBm. A minimum threshhold for a GSM call is around -105. You should read the article (I don't fully understand it), but to summarise, it seems the scale doesn't have a way to express theoretical zero—it goes all the way down to negative infinity. (Source and more figures: http://www.howardforums.com/showthread.php/1523050-dBm-signal-strength-on-GSM-acceptable-numbers?s=604fff0acef77fc792c87beff84fcc5a&p=12531271#post12531271) —Noiratsi (talk) 10:49, 15 December 2014 (UTC)

In the spirit of disclosure, we don't know that the display is showing data in units of dBm - although that is one common way to express such signal levels, there are many other methods and units. For example, received signal strength indication (as standardized by the IEEE 802.11 WiFi specifications) has arbitrary units; and it is permitted to vary between vendors and implementations; so there is no real way to relate its value to any physical parameter. Proprietary techniques for signal strength indicators proliferate widely in the consumer radio industry!

Nimur (talk) 17:00, 15 December 2014 (UTC)

To answer the theoretical part of the question, the thermal noise floor at 25°C with a 50 ohm load is -147 dBm/Hz, so for a single GSM channel with a bandwidth of 200 kHz, the noise floor is at -121 dBm. (Copper would be better than lead, incidentally - see Faraday cage.) Tevildo (talk) 01:35, 16 December 2014 (UTC)

What disasters were caused by bad programming, bad software development?

I see that software providers cover their back with a 'no guarantees' clause, but what has happened already due to buggy software?--Noopolo (talk) 19:05, 15 December 2014 (UTC)

http://archive.wired.com/science/discoveries/news/1998/07/13987 Divide by Zero error in a navy ship. Avono (talk) 19:34, 15 December 2014 (UTC)

Therac-25, Mars Climate Orbiter#Cause of failure. -- Finlay McWalterᚠTalk 19:40, 15 December 2014 (UTC)

The 1990 AT&T Long Distance Network Collapse

Wikipedia has an interesting article List of software bugs. Since it only covers bugs that are notable in some way, a bunch of them might qualify as "disasters". APL (talk) 00:52, 16 December 2014 (UTC)

This list was constructed from articles posted in the Risks digest over the years. Not all of the items are examples of "buggy software"; see the table of descriptor codes near the top. --65.94.50.4 (talk) 04:00, 16 December 2014 (UTC)

Which Linux distribution?

A friend of mine contacted me to say he has an old laptop running Windows 7 that he wishes to replace with Linux. I'm assuming the laptop is already several years old. I don't know its exact specs yet as I've not seen it yet. Which distribution should I use? The only distribution I have myself ever used is Fedora, and Red Hat before it became Fedora. My friend knows his way around Windows, although he has no training or experience in programming or system-level work like me. I'm assuming he has no previous experience of Linux, but should quickly pick it up once he sees it. JIP | Talk 19:34, 15 December 2014 (UTC)

Xubuntu -- Finlay McWalterᚠTalk 19:41, 15 December 2014 (UTC)

Yes, or try to boot a 32 bit Linux Mint. When this live CD etablishes the desktop, it is possible to install it from desktop. --Hans Haase (有问题吗) 19:44, 15 December 2014 (UTC)

Yes, Linux Mint.--Aspro (talk) 10:54, 16 December 2014 (UTC)

What is Blipp?

An ad in my newspaper (which I get home delivered, so I'm talking about something I saw on paper, not online) tells me to Blipp. This seems to be connected to Blippar. Neither has a Wikipedia article unless this is somehow connected to Blip (website).— Vchimpanzee • talk • contributions • 19:57, 15 December 2014 (UTC)

g returned no:Stian Blipp or blippapp --Hans Haase (有问题吗) 20:16, 15 December 2014 (UTC)

I get something called "augmented reality advertising" but I'm not interested in the type of marketing-speak Wikipedia avoids.— Vchimpanzee • talk • contributions • 23:08, 15 December 2014 (UTC)

Videos for youtube

I am attempting to upload 6 different 40 minute albums up to youtube. My songs I made are around 12mb a song and I compiled them into on long mp3 file of the album just for youtube use and when I use Windows Movie Maker to take a picture/album cover and use that as the image for the youtube video the files end up being massive for some reason. All it is in the movie maker is the audio files aka mp3 files and they are about 50mb in total and the image is less than a mb in size. How can I Use my image and add the audio to it so it doesnt take up to much video space? The video files take for ever to finish and they are up to 350mb in size. — Preceding unsigned comment added by 204.42.31.250 (talk) 23:00, 15 December 2014 (UTC)