Why does my computer randomly reboot without warning?

Please Please Please DO NOT VACUUM YOUR COMPUTER. If you want to build up a static charge and kill components, this is an easy way to do so. Computer stores sell compressed air for a reason.

Things to look for to provide further diagnosis

1. Capacitors - google image search this to get an idea for what they look like. They should not appear to either leak or be "pregnant". If they are smooth on top, and not leaking, you are good. Otherwise you are not.

2. Download a bootable copy of Knoppix Linux and burn it to CD. Run it on randomly restarting computer. Go on internet etc, and just try leaving it on for a while. If it doesn't restart, you are likely (but not 100%) dealing with a software issue that has made windows unbootable, or some other software issue which causes random crashes.

3. In this modern day and age, cooling can be rather critical. Your video card, CPU, Northbrdige and Southbridge should all be cooled. Random power offs can be caused by any. The CPU and Video cards will have fans. Watch the fans and see if they stop spinning or struggle to spin. Please note that your computer will likely slow the fans down in order to keep your machine quiet, so slow fans may also not be the issue.

4. While the power supply could be the issue, the power cord could also be an issue too. Try a different one. If issue persists return it to Best Buy for full refund. A nice solution that doesn't violate your warranty.

Cleaning out your computer with compressed air can also help. The most important things to check over are "Did I make a recent change" as this would likely be the cause, and if not "Is everything in here working". Eliminate the fans by watching/cleaning/replacing them, eliminate software with the knoppix, then start looking at the other culprits - leaking caps, and bad Power Supply.

my domputer does not start normally and reboot repeatedly
how can i restore my pc through cmd to an ealier time.
thank.

I had a sp2 in my Lenovo computer but when I switched to Windows vista after some time it gives blue death screen and sometimes it rebooting again and my warranty period has been over so I moved to Computer repairs sheffield and got a solution from there , actually it was not because of changing the OS but because of some registry problem and somewhat other problems so I advise to try registry cleaner for this problem.

Have the same prob, the main power supply is overheat and if u cont, it will burn causing loss of memery.

This sound like the system is over heating. clean the systems fans out as CPU's have a fail safe which switchs the machine off or restarts it. I see this alot on laptop repairs.

Click here to read an article about troubleshooting random computer restarts.

I recently built my current system and it works great when just doing general everyday computing, but when I try to play Age of Conan, I can only play a few minutes before my computer reboots. I thought it was an overheating issue as I installed Speedfan and saw my CPU would heat up to 55-60C and GPU would reach 70-75C before reboot. But I can play Lord of the Rings and while the same temperatures are reached, my computer doesn't reboot. I contacted AoC tech and they tell me they know of no know issue that would cause this and it sounds like a hardware issue. Well, if it were a hardware issue, why doesn't it happen when I play LOTR?

Operating System: Windows XP Professional (5.1, Build 2600) Service Pack 3 (2600.xpsp_sp3_gdr.100427-1636)
Language: English (Regional Setting: English)
System Manufacturer: System manufacturer
System Model: System Product Name
BIOS: BIOS Date: 05/21/10 12:07:52 Ver: 08.00.15
Processor: Intel(R) Core(TM) i5 CPU 750 @ 2.67GHz (4 CPUs)
Memory: 3580MB RAM
Page File: 479MB used, 4983MB available
Windows Dir: C:\WINDOWS
DirectX Version: DirectX 9.0c (4.09.0000.0904)

Card name: NVIDIA GeForce GTX 275
Manufacturer: NVIDIA
Chip type: GeForce GTX 275
DAC type: Integrated RAMDAC
Device Key: Enum\PCI\VEN_10DE&DEV_05E6&SUBSYS_0E0619F1&REV_A1
Display Memory: 896.0 MB
Current Mode: 1920 x 1080 (32 bit) (60Hz)
Monitor: Plug and Play Monitor
Monitor Max Res: 1600,1200
Driver Name: nv4_disp.dll
Driver Version: 6.14.0012.5896 (English)
DDI Version: 9 (or higher)
Driver Attributes: Final Retail
Driver Date/Size: 7/9/2010 18:38:00, 6343040 bytes

I got this problem for about one year now and just can't and can't fix it, my dad already tasted my video card, Processor, RAM and motherboard, it still kept rebooting or freezing randomly, the next step was installing Linux and putted the Processor to 99% performance, it ran for around 2 days and the comupter didn't reboot. after I went back to my windows XP and it rebooted again, than I even installed windows 7 and still rebooted. today I even changed my Hard Disk and it is still rebooting sometimes.. I dont know what to do anymore

I have a problem with random reboots and I am runing Vista. I have virus and spyware protection on my system. Often when the computer reboots the graphics are out of sync. Are there any other areas that I should look into?

The article you just commented on has the general approach. Beyond that it would take more details or a technician to take a look at the machine.

12-Feb-2011

So since we on the topic of computer randomly rebooting I have my question. My computer will randomly restart when playing video games. Ive replaced the motherboard, processor, ram, power supply, videocard, everything but the case and CD rom. Im running a I5 750 8 Gigs of DDR3, GTX 275, WIN 7 64 Bit, 1200 Wat power supply. After i have replaced everything it STILL does it. Any ideas. During this last buid I put on a water cooling set so I KNOW its not over heating. Fresh install of WIN 7 and every driver is up to date. The only thing left is my case. ITs an antec 900 Case. Ive read a lot of forums and i havnt read anything suggesting that it could be the case but besides that it is the CD ROM. ANY Help would be appreciated. I took my computer to a shop and they have no idea what it could be everyone is STUMPED.