This post has been, and will continue to be, edited as new stuff is added and errors are corrected. All contributions both corrective and additive are gratefully welcomed.
Good luck with your fix.
Motherboard's Basic Troubleshooting Guide.
This guide is meant to get the reader through some simple procedures for troubleshooting their PC. Please read all of these notes before posting a problem on the board because some problems are common to both existing and new builds and may not be repeated in the part you didn't read.
My computer was running fine but now it does not switch on at all; the monitor is black and I can't hear fans or other noises from the PC and there are no lights on the PC or monitor. It's totally dead.
First, unplug everything from the mains supply. When disconnected push the on switch in for a couple of seconds - this discharges the capacitors. Leave disconnected for 10 minutes or longer. Plug everything back in and try again. This has been known to work when there's been a power surge or glitch. It's a long shot but could save a lot of time and pain.
Then, check the obvious:
· The power leads to the PC and monitor are properly connected and the power sockets are switched on. Sometimes power leads can be knocked out or loosened by cleaning. Remove and re-connect.
· If there is a power-switch on the monitor and/or PC, check that they are in the "on" position. These switches are usually found at the rear near where the power supply cables enter the unit.
· The plugs on the power cable leads have not blown fuses.
· If you use an extension cable with several output sockets, test or replace it.
· Confirm that the mains outlet itself is working.
If all is well there we need to check that the on switch itself is ok on the PC. To do this you need to open the PC and find the small connection block (header) where the pair of wires attach. Either trace these back from the switch or check with your manual which these two are. Pull the connectors off (they're just a push fit). Make sure everything it turned on and touch the two pins simultaneously with a screwdriver - just short them out briefly, don't leave the screwdriver on the pins. The PC should start if it was just the switch that was nfg.
If there are still no signs of life at all it is likely to be a Power Supply Problem (PSU) but it could also be a motherboard or memory failure. See later.
The computer will switch on, I can hear the fans humming, but the screen is black.
When the PC is first switched on the red and green LEDs (lights) on the front of the PC should light up with the red finally going out after a minute or two. Also a green light on your keyboard should blink on and you may hear one "beep" from the system speaker. This means that the PC has successfully started itself up but it may not have proceeded to load Windows.
(The keyboard lights are a built-in diagnostic tool. One brief flash or two as power is applied, followed a few seconds later by another flash, indicates a working system. Without that second flash, the system has encountered a Power On Self Test (POST) critical error, and halts).
Watch also what happens to the small LED on the front of the monitor. When you switch the PC and monitor on it should power up to give a permanent green. If your LED does not light at all, the problem could be down to the monitor alone. In this case check that:
· The power lead to the monitor is properly connected and the power socket is switched on. Sometimes power leads can be knocked out or loosened by cleaning. Remove and re-connect.
· If there is a power switch on the monitor, check that it is in the "on" position. These switches are usually found at the rear near where the power supply cable enters the unit.
· The "on" button, usually on the front bottom right, of the monitor has been pushed J
· The plug on the power cable leads have not blown a fuse
· If the monitor is a thin, flat one (a TFT), check that the power supply transformer unit is plugged in and working.
If the PC LEDs and the keyboard LEDs are on as described and you've heard a single beep from the loudspeaker AND you've heard the windows theme tune it means your PC has started normally but the monitor cannot display it for some reason.
If the monitor LED goes amber or blinks green off and on, it's telling you it is not receiving a signal that it can use from the PC. First check that
· The cable connecting the monitor to the PC has not become disconnected at either end. Remove and re-connect it anyway.
· If you've been fiddling with things, check that the pins in the cable connectors are not bent or broken. Bent pins can be straightened with long nosed pliers. If one breaks you need a new cable.
· If you have one, change the cable with a known working one. (Modern monitors have a "hard wired" connection at the monitor end rather than a plug and socket arrangement that makes this test difficult.)
· Turn up the brightness on the monitor to about 2/3 full.
· Exchange the monitor with a known working one.
· Your video card may be broken or have come loose. Remove and reseat it. If you have an "on-board" video out or a spare video card try that. Some cards need their own power supply, check that is plugged in.
. Some new motherboards need a second 4 pin power supply connector as well as the 20 pin ATX connector; check it's plugged in.
The PC starts, the monitor works and shows some output but Windows won't load
What's happened here is that the PC has booted itself up and tested and loaded the hardware components it sees in it's system and is displaying some of it. When all is well, it looks for the operating system. Depending on how this is set up on your machine, it looks first on a floppy drive, then on a CD drive and then on the hard drive. When it doesn't find it or finds a corrupt version, it fails.
There are several things that could have happened but, as this is a recently working PC, here are 3 things to check first.
1. Switch the PC off at the mains, wait for a couple of minutes or so, then restart. Try this two or three times. Sometimes this is enough to bring it back to life without further work.
2. Check that your machine's Basic Input Output System (BIOS) has recognized the hard drive during its boot process. To do this:
· Restart the machine
· As soon as the machine begins to start up again regularly press the key that enables you to enter the BIOS. This key will be found in your motherboard manual and can be esc, F2, F10 or Delete.
· Go through the menus and check that the BIOS has properly identified the hard drive. If it hasn't, check that the Auto detection box is enabled Save and exit
3. To Clear the CMOS.
Open the case (switch off and pull the power lead out first!). With the power cable unplugged, push the PC's front power on switch; this drains any remaining charge held in the motherboard's capacitors.
On the motherboard (the main circuit board), usually near the small silver battery, you'll find a group of three small pins with a jumper (a small clip) on two of them. Remove this jumper and put it across the other two pins & the center pin being common to both these settings - count to 20 or so then put the jumper back into it's first position.
4. While you're in here it's worth removing and testing the battery or replacing it.
5. Plug the mains back in, switch on and cross fingers.
New Build Troubleshooting or,
I've just finished building my new machine and it doesn't b****y work.
We've all been there. It's probably taken you a long time, a lot of effort and a lot of money to get this far so it's worth taking a little time out here.
The first thing to do is to pour yourself a cold beer, gather all the manuals from the components around you and sit down somewhere comfortable. You need to confirm to yourself that what you have is actually designed to work with each other. Check particularly that:
· the PSU is up to the job. A modern, fully fitted, machine will need at least 350 watts of output (some now say 450W) with 28A on the +3.3V rail, 35A on the +5V rail and 16A (some say 25W+) on +12V rail. More of each is better. Less of any may be problematical. If you don't have a manual for this, you'll find it written on the PSU label.
· Your chosen memory is compatible with your motherboard. Obviously radically different memory modules won't physically fit into the RAM slots but there are many less obvious technical reasons why some will not work. There's no escaping RTFM.
· Does the CPU really match the motherboard or were you just hoping J. (It must have the correct voltage, speed, multiplier settings chipset and BIOS versions as well as just fit into the socket.)
If you're satisfied that everything is compatible, the fastest way of sorting it out is to do a minimal build. To do this I'm afraid you have to disassemble the machine. Take everything of the motherboard and take the motherboard out of the case (for the moment leave the CPU, heatsink and fan in place.) Lay it all out on a table - generally people say put it on cardboard or other non-conductive material. (the anti-static bag that the motherboard came in should not be used as it is conductive). As always, take whatever precautions you think necessary to avoid static damage; the minimum is to touch the bare metal of the case before anything else but use an anti-static strap if you have one.
New motherboards turn off automatically if they don't get information from CPUFAN (most of the time CPUFAN1); this tells the motherboard that the fan is spinning in order to prevent the CPU overheating and burning out. So make sure you always plug your CPU fan into this power slot on the motherboard instead of SYSFAN or AUXFAN or any other power connection. (note: sometimes CPUFAN isn't the closest one to the socket.)
Plug in the PSU connector to the motherboard, ONE stick of RAM, and, if the motherboard doesn't have its own monitor output, slot in the video card too. Some video cards require their own power connection from the PSU; check your video card manual. If you can, also connect the case speaker. Connect the monitor. Note that we don't need any hard drives at this stage.
Remove the motherboard battery and move the CMOS jumper to the clear position (check your manual for this). Put the battery back in, wait a few seconds then put the jumper back into the start position.
Plug into the mains (PSU and monitor), switch on the PSU and start the "barebones" PC by touching the two power-on switch pins with a screwdriver. (Again, you may need to check your manual to identify these.) With a bit of luck the fan will spin, you'll hear the speaker beep once to say all is well and the monitor will show the progress as it loads its basic input output systems (the BIOS). The PC will fail as it attempts to load the operating system, which it doesn't have yet (because it doesn't have a hard drive or CDROM drive to load it from, but you've proved that the base machine works.)
If all is well switch off at the PSU and add components one by one, starting with the rest of the RAM until one either fails or the machine is fully working.
Assuming all now works you can re-install in the case. Before you do that though carefully check that the small brass standoffs or spacers that the motherboard rest on in the case are in exactly the right places. The standoffs perform three tasks:
1. they keep the motherboard stable and in the right place
2. they prevent the base of the board shorting out against the case
3. they ground the board in the places that the designers consider need grounding.
For these reasons there should be a stand-off wherever there is a hole with a sliver solder ring in the board and nowhere else. If you have a brass stand-off under a place on the board without a hole you could short it to earth and destroy it, so do check this carefully. (Sometimes boards come with small plastic clips & you'll need to check your manual to confirm where these should be placed & normally they will be used where the board needs support but must not be grounded)
Once fully installed back in the case and having checked that it boots into the BIOS screen you can go ahead and install the Operating System.
If it doesn't work once it's back in the case, you'll need to check and recheck all the connections again.
Ok, I've tried the minimum install and it still doesn't work.
This is a nuisance but at least we know that the problem is with the PSU, memory, motherboard or CPU. The first thing to do is to check or replace the motherboard battery and to check that the CMOS jumpers are set in the start position (pins 1&2) as some motherboards are set at clear (pins 2&3) by default to save the battery. Try again.
Then remove and reseat everything except the CPU and fan. Try again.
Then try the memory in another slot. Try again.
Next you need to take off the fan, heatsink and the CPU. Check that there are no bent or missing pins on the CPU. A bent pin can be carefully straightened but if it breaks it's toast. Reseat and try again.
(Removing the Fan from the CPU gives you the problem of having broken the heat sink/CPU heat transfer seal which is why we did it last. The seal is either a small gray pad or a greasy smear of something like Arctic Silver compound. If you used the compound, re-apply it, otherwise get another pad. You need to remove the old one with something like the edge of a credit card so that the surface of the CPU and heatsink is not damaged (don't use a knife!) and remove any residue with Isopropyl Alcohol.
You can use compound and that will work, probably better than the pad as far as heat transfer is concerned, but it may void your guarantee.)
If after all this it still refuses to boot you are running out of fix it yourself options. If you have known working spares, test using them; PSU, Video Card, memory, CPU.
The *Really* Minimum Build, last resort, procedure.
These tricks can help identify very basic hardware problems. You have to switch off and restart between each step.
With just the CPU, keyboard and the speaker connected to the motherboard (ie no PCI cards, no video card, no memory, no mouse, no hard drive, no CD/DVDROM, no floppy drive) try to start the PC by shorting the power on pins with a screwdriver.
If there is no beep from the speaker, either the motherboard or the CPU is dead. Several beeps indicate that they are alive. Now add one stick of memory. One long followed by several short beeps should then indicate you have a video problem (unless you have onboard video). Put in your video card and you should get basic video.
General Troubleshooting Tips
1. If the system is totally dead, no beeps, no fans, black screen; suspect the power supply first but other problems could be a dead motherboard or failed or incompatible memory
2. If the system is locking up during POST it could be caused by any or all components being incorrectly installed but suspect first memory and video cards
3. If you get a single beep from the system speakers and the fans are running but you get the black screen; suspect the video card
4. No beeps, black screen but running fans, suspect CPU
5. System locks during, or just after, POST; check CPU temperature for overheating. Check that the motherboard is set for the correct CPU voltage, motherboard bus speed and clock multiplier.
Here are some other points to consider:
· If your motherboard has an auxiliary ATX power connector (square 4-pin) as well as the usual 20 pin one, make sure that it is plugged in.
· Do you get beeps from the speaker during your tests? Write them down and try to match them with anything it tells you in the motherboard manual. These are Power On Self Test (POST) procedures and will tell you at what point the PC failed to load itself. Often these POST signals are output to a LED display on the board. Again check against the manual. (These outputs can give you information that you can't understand but they may help you describe the situation better to either the place you bought it from or us here at Motherboards)
· If the fan on the CPU starts the PSU outputs can be tested using a digital multi-meter.
· You can test memory in a working PC by using the free memory tester, memtest or Microsoft's version
· If the computer turns on for 1-3 seconds and either beeps extremely fast or (most often) just turns itself back off you may have plugged the CPU fan into the incorrect power slot. Confirm that it is in CPUFAN or CPUFAN1.
Virus, Malware, Trojans, Spyware etc
If your PC has been suffering from slowdowns, pop-ups, web browser diverts and weird behavior generally it may have viruses, trojans, spyware or other malware. You need to clean it up with good software. We recommend the free AVG or AntiVir virus guards (use only one) and the free SpyBot search and Destroy, Adaware and Microsoft's free AntiSpyware for spyware (you can use all three). Additionally you may need hijackthis; a small (free) program that shows what's loaded on your PC. Google for them.
nb. If your system is very badly infected, sometimes it's faster and safer to format and re-install. If you don't want to format and re-install here's the procedure for a clean up.
you'll have to go about this in a systematic manner.
1 start in safe mode, go to add/remove programs and uninstall anything you don't recognize or looks dodgy.
2 uninstall any old virus guards or update the one you use.
3 get AVG (only if you have no other virus guard installed, only ever use 1 virus guard), Spybot, AdAware, microsoft's antispyware and install hijackthis. get them all up to date
4 get all the XP updates
5 get ccleaner (www.ccleaner.com)
note: some people advise turning off the system restore function before attempting to clean the machine. On balance, this is not a good ploy as it will delete your system restore points making it impossible for you to recover if things go wrong. It's better to clean your machine, create a new restore point, then delete previous ones that may still hold the bug.
Here's a link about how to remove just some of the restore points XP creates automatically.
unplug your PC from the net and run all the programs one after the other, leaving hijackthis till last.
when you've run everything and cleaned up after with crapcleaner run hijackthis and parse the logs in the www.iamnotageek.com site or http://www.hijackthis.de/index.php?langselect=english. It will highlight anything it doesn't like.
Hopefully you'll get an all clear but if not, post your problem in the Virus/Spyware/Security forum.
(We don't recommend you remove entries yourself unless you know what you are doing)
When you've finished, it's a good idea to Defragment your hard drive to get everything straight again.
(Start-->Programs-->Accessories-->System Tools-->Disk Defragmenter)
There's a great guide to spyware removal here:
If you get Blue Screen of Death (BSoD) or Stop Errors occurring there's a troubleshooting guide here
http://support.microsoft.com/default.as ... -us;324103
How to Resolve IRQ resource conflicts
(This procedure is from the magnificent Karlsweldt)
Remove the power cord, and do the CMOS clear routine. Up to 15 seconds with the jumper in the "clear" position will do no harm.
Ensure the sound card is in the slot closest to the video card. Sound cards require a more complex data stream than any other device, next to the video card. But the AGP bus is separate from the PCI bus. In order of importance, there should be the video card, then the sound card, followed by the LAN or Network card, after any other drive device such as SCSI or SATA. The modem should be in the last available slot.
On powering up, look in the Bios pages under "PCI/PnP" for a line reading "Reset Configuration Data" which will be [disabled]. Change this to [enabled], save, exit and reboot. If there is a conflict with resources, the BIOS will sort them out prior to the OS doing its task. The setting is a one-shot only, and reverts to [disabled] on next viewing, which is default. Not all BIOS types have this feature presented. It may be automatic.
The PCI slots nearest the video slot are the highest in priority, being lower than a 10 IRQ. Reserved IRQ assignments for the ports, system clock and real-time clock as well as the IDE controller and CPU/FPU cannot be shared. Others can, and a "cascading" or "steering" IRQ controller is employed, which shares a higher number IRQ, but lower priority, with a higher priority but lower IRQ number.
If there are 3 devices on an IRQ, there should be no conflict, unless the sound and video share the same IRQ.
Typical IRQ assignments, for the AT/ATX setup: 16-bit/32bit ISA/PCI/AGP
0 = System Timer
1 = Keyboard Controller
2 = Second IRQ Controller Cascade (Also known as a PIC, or Programmable Interrupt Controller)
3 = Serial 2 Port (Com 2, Com 4)
4 = Serial 1 Port (Com 1, Com 3)
5 = Sound System, or Parallel Port 2 (LPT 2)
6 = Floppy Controller
7 = Parallel Port 1 (LPT1)
8 = Real-time Clock
9 = Available as IRQ 2 or IRQ 9 (Cascading)
10 = Available
11 = Available
12 = Mouse Port (PS2) and available
13 = Math Coprocessor
14 = Primary IDE
15 = Secondary IDE
IRQ assignments above 15 are handled through the cascading provision of other ports.
Power Supply Notes
Caution, the PSUs contain high voltage capacitors which maintain a charge, even after the power is disconnected, and can be fatal or at least provide a nasty jolt if touched. If you are determined to poke around inside one be very careful. Opening the case of a PSU will normally invalidate any guarantee you have on it.
The Power Supply Unit (PSU) rather surprisingly, supplies the power to the computer. It takes mains voltage and transforms it into the 12 volts, 5 volts and 3.3 volts of Direct Current (DC) the PC needs to operate.
The PSU has to be accessed from inside the PC case. The only things that can be checked externally are:
· The power lead to the computer is properly connected and the power socket is switched on. Sometimes power leads can be knocked out or loosened by cleaning.
· If there is a power-switch on the PSU, make sure that it is in the "on" position.
· The plugs on the power cable lead has not blown a fuse.
· Sometimes there is a small slide switch that determines the input voltage and Alternating Current (AC) depending on the country you are in. 240V and 50 Hz (UK) or 120V and 60 Hz. (USA). Check that this is correct for your region.
Without expensive load testing equipment the PSU cannot easily be tested if the PC fails completely to power up because without a load being applied, the PSU will not output. If the fans on the CPU spin, the outputs can be tested by probing connectors at the motherboard.
The cheapest and quickest way to confirm a PSU as dead is to test the PC with a known good PSU.
Occasionally the fan inside the PSU will fail. This is very likely to cause the PSU to overheat and fail and the PC will shutdown. When this happens there can be an unmistakable smell of electrical equipment burn. Before a fan fails it will often become very noisy as the bearings gradually give out. It is obviously best to change out the PSU before this happens.
If the PSU manages to struggle on with a broken or a semi-disabled fan, it can cause the PC itself to overheat. A sudden shut down of the PC is one indication of overheating as the CPU tries to protect itself. If you touch the case around a PSU with a troubled fan it will be hot.
Fans inside PSUs can be replaced as they tend to be standard components. There is also a fuse inside the PSU which can be checked if necessary but please take notice of the safety issues above.
While you're in there, it's worth checking for swollen and leaking capacitors which will cause the PSU to behave erratically and eventually fail. If you're competent, they can be replaced, but you're better off binning it and buying new.