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Does laptop charger wastes electric current when not connected to the laptop?

Wonder if when I leave it connected to the outlet but not connected to the laptop, it still consumes electricity.

Should laptops remain plugged in when their battery is 100% charged?

When your laptop's battery is 100% charged, should you leave it plugged in so any battery power doesn't get used, or will that cause overcharging, overheating, etc.? Should the laptop be unplugged when the battery level is 100%?

I'm asking because my laptop's screen tends to get dim when unplugged, so I don't like to run it on battery.

Why are my games slower on battery power, even with the power plan set to High Performance?

My laptop is capable of running most games on high settings at decent frame rates. However, if the power cable gets unplugged while I'm playing, the game immediately starts slowing down, even if I'm using the High Performance power plan.

Why does this happen? Is the battery not able to keep up with the power demands of the GPU? Is there any way to fix this?

Can touching any hardware inside a running PC be dangerous for you?

I'm curious, if all the hardware gets power from the PSU's DC power lines, which provide a max. voltage of 12V, can you get electrocuted by touching some of the hardware?

Why are brownouts so harmful?

I was reading http://superuser.com/questions/32840/is-surge-protection-actually-needed and well I'd like to know why brownouts are so harmful. The explanation gave there is "the capacitors get above their rated voltage" But that makes no sense if the power coming into the PSU is less than the usual voltage. What happens to a PSU in a brownout to damage it?

Is there any protection built into modern PSUs to prevent such damage? Is there any way to protect the computer in brownout conditions other than using a UPS?

Pulling the plug out for 10 seconds

When calling support the other day he told me to reset my DSL modem by pulling out the power, leave it out for 10 seconds, and then plug it back in. This is something I have heard many times with different kinds of equipment. I have also heard it in relation to computers. That when you turn it off, you should wait at least 10 seconds before you turn it on again.

• Why not just plug it in again right away?
• Why 10 seconds, instead of, say... 3 or 30?
• Should you really, always do this; just with certain types of equipment; just in certain circumstances; or is it just a "myth" thing that people have said so often that they believe it to be fact?

How to choose a UPS / calculate power for a new PC

Seven years ago a friend gave me a Liebert PowerSure 250 UPS and it has done well for whatever (home) PC and monitor I've plugged into it over the years. I've just ordered a new PC with the Intel core i7-920 and other nice specs for 3 HDDs, a nice graphics card etc, and opted for a 700W power supply.

I'm guessing the new workstation will use a lot more power than my current Shuttle box (this will be a development machine running SQL Server). I found a UPS selector wizard which suggested I should choose a UPS capable of providing 524VA - my current UPS is only capable of 250VA.

I've read good reviews for an APC Back-UPS ES 700VA - which is 700VA, but it's output capacity is only 405 Watts. Does that mean the 700W power supply in my new PC is over-spec'ed? Or have I missed something? I only want the UPS to run for 5 minutes in the event of a power-cut. How do you choose a UPS to cover your power requirements?

How to test a power supply?

My computer powered off the other day on its own, and now when I push the power button, nothing happens. My assumption would naturally be that the power supply is done (possibly well done) but is there any good way to test this before I buy a new one?

What is the power output of a USB port?

As the title says, what's the power output of a USB port?

Is it a standard value, or it may change depending on manufacturer/model, and so on?

If that value is not standard, how can one determine it?

What kind of power port is this?

I'm planning on getting a new PSU and I was shopping online when I saw this thing.

What kind of port is this? I've never seen it before, and I definitely can't find cables for this.

For reference, this is a "normal" 3 prong cable:

The PSU itself is a NZXT HALE90 850W.

Why do some AC adapters and power supplies generate a whining noise, and what can I do about it?

I have many different AC adapters and power supplies for a variety of devices, ranging from small 5V/1A USB chargers to laptop power adapters and desktop PSUs. However, I often hear a whining noise from some of these power supplies. This happens most often when they are not connected to a device or otherwise in use, and stop making noise when I connect a load to it such as by plugging in a device that is not fully charged.

Why do some AC adapters and power supplies make this whining noise? Why do some not make this noise? Is there anything I can do to suppress it?

My 386sx refuses to start in cold days

My old computer refuses to start in cold days. So, in really hot days (about 40ºC / 104ºF ) or even hotter, this PC usually starts, but in cold days, it wont.

When the temperature is not in the "sweet-spot" the power light turns on for an half a second and then the computer turns off. But when it's really cold, not even the power light turns on, nor even a blink. Sometimes I use an Hair dryer, pointed directly to the PSU and that works great. 5 to 10 minutes is enough, depending on the ambient temperature. I think something is going wrong in my AT power supply.

I can't replace this PSU for another because it has a non-standard size and connectors to power the motherboard.

Does anybody have a clue about what it's failing in my PSU, so I can change that component (resistor, capacitor, ??, etc) and rock on with my 80386?

This is a Schneider EuroSX, manufactured between 1989 and 1991 (I guess)

PSU Info:

Inside PSU:

Will leaving the laptop power brick connected to the power socket be dangerous?

My co-workers (who worked with the company longer than I have) loves to remove their laptop's power cord when they need to move around the office.

I frown on this practice since they usually don't remove the power brick from the power socket. I've told them numerous times that its dangerous to leave the brick unattached to the laptop and that they should remove it from the socket if they need to move around.

I think I need a better argument on why they should stop this practice. Does anyone has any experience to share to discourage this behavior? Is there a research or article somewhere that shows how much power is wasted?

Edit: If you think I'm wrong and leaving the power brick connected is not dangerous, go ahead and prove me wrong. :)

PC shutting down after 30 minutes, even when on BIOS screen

I have a desktop PC that is just over a year old that I use daily for work. It's running Windows 8.1, has 16GB RAM and an i7 CPU. It has a 256GB Samsung 840 SSD (Windows + programs) along with a 1TB Seagate HDD (documents). The motherboard is an ASUS B85M-G. The graphics card is a 2GB ZOTAC GT640, with two monitors attached.

As of Friday last week it is shutting down (without warning) after 30 minutes of uptime. I have not installed any new hardware recently, nor installed any new software (other than whatever Windows updates came along last week).

By "shutdown" I mean that it is as if the power cable was pulled from the PC. Screen goes blank, cooling fans stop spinning, and I can hear a "ping" from the 1TB HDD as the drive head parks.

Initial speculation suggested that this was a classic PSU issue, so I obtained a replacement power supply and plugged that in this morning. Same problem.

While in Windows I have run temperature monitoring software that shows that the CPU cores are happily down at around 40°C, and the GPU is at a similar temperature. The innards of the PC are clean and free of dust, and all fans are spinning.

BIOS reports that CPU temperature, fan speeds and voltages are fine:

Following a shutdown and restart I've inspected the Windows event logs, but have not found anything that explains the shutdown, only a log entry that says that Windows was not shut down properly.

I have also discovered that the problem persists if I just enter the system BIOS on boot and let the PC sit there for half an hour (so it's not a Windows issue...)

I have upgraded the BIOS since I bought the PC, but this was back in May.

I have checked the RAM using Memtest86+, this reported no issues but sadly was only able to get about 60% of the way through before the PC shutdown.

For what it's worth, there is very little clearance between the heat sink on the passively-cooled graphics card and the RAM. However the heat sink is generally cool to the touch. There is also not much clearance between the CPU heat sink fan and the graphics card, but again temperatures are fine. Photo below illustrates the internals...

Can anyone suggest what might be going on here?

Edit - Troubleshooting progress

Since originally posting this question I've tried the following in an attempt to isolate the issue. In all cases the PC still shutdown after 30 minutes:

• Unplugged optical drive, entered BIOS screen
• Removed graphics card, allowed to boot to windows (presumably, as I remembered I'd previously disabled onboard graphics in BIOS so couldn't get a picture on my monitor
• Replaced graphics card with another, unplugged all USB devices apart from mouse and keyboard, entered BIOS screen
• Unplugged SSD and HDD, entered BIOS screen
• Removed backup battery for BIOS, waited half an hour, put battery still in. Booted and went to BIOS screen

Can PSU cause my PC to reboot?

I'm having an issue with my PC: It is rebooting sometimes, and I am suspecting the PSU, so I want to confirm a few things. It is a new PC and the first issues started occuring roughly one month after purchase. Also they only occur after several hours of usage. And it seemed that completely shutting down powerline to the PC, and waiting few minutes, then putting it on again, seemed to relief the issue, but that might be just coincidence?

First off:

• Does the PSU capacity decrease over lifetime of the PSU?
• Does the PSU capacity temporarily decrease as it is active for a continious time?

My PC specs: Intel i7-3770, 16GB RAM, GTX 770, SSD, HDD. I think Asus Z77 motherboard.

As you can see it is pretty high-end, but I rechecked the PSU on the invoice yesterday and to my surprise I found a 30 euro PSU, namely the HKC V-550.

My system draws 480W of power from the powerline, if on full GPU & CPU stresstest. This is a heavily modified version of their base system, which did not include such a high-end GPU as the GTX770.

Also, as far as I know, a system shutdown (without! bluescreen) can only occur, if:

• PSU shuts down
• CPU shuts down
• Motherboard shuts down?

But to me it occurs to be logical that the PC would not reboot if the CPU or Motherboard had shutdown, yet with a PSU and a safety switch it might seem logical that it could reboot.

Also about the reboot: The PC "on"-LED in the front turns off once it reboots, and in my headset (that is connected through USB) I heard some kind of clicking sound once when it turns off, and once when it turns on. Might that be enough reason to believe that it is the PSU?

Also, the temperatures of my CPU and GPU, actually of my whole PC, are perfectly fine under load. The only real test I have not been able to do yet is Memtest86, but wouldn't that lead to a bluescreen under windows anyway? Instead of a reboot.

Well I hope someone is able to help me here.