Tips and Tricks



MoBo Power issue

By colin_duryea ·
I am working on a client's PC and am in the process of replacing the motherboard. All connections (to the best of my knowledge) are connected and when I press the power button, all the fans go on and it sounds like its on. Nothing else happens though, the harddrive isn't spinning, the video doesnt display. Its just the fans that turn on and thats it. What could cause a problem like this? I want ALL possible problems. So far this is what I've come up with.

-weak power supply
-screws maybe?
-bad MoBo

I don't know. I can't think of anything else. Does anyone have any neat tricks I can do to maybe get this system to work?

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All Answers

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Well a bit more detail wouldn't have gone astray

by HAL 9000 Moderator In reply to MoBo Power issue

But if it's an AMD M'Board you could have a incompatibility between the Video Card & M'Board. That's very common even when the M'Board & Video Card are from the same maker or have the same chip set brand on them.

The PS could be on it's way out so I would suggest that you test it with a Known Good one to see what if anything happens.

The Jumper for the CMOS could be set to clear and not allowing the system to actually start.

The CPU could be fitted the wrong way around and not working at all if it's still capable of running

You could have a faulty HDD or other Optical Drive that is pulling the available power low and preventing the unit starting.

You always could have a faulty M'Board but unless you didn't follow normal Static Control procedures correctly this is unlikely unless it's one of the cheap nasty ones.

The CPU from the Old M'Board may not suit this new M'Board.

The monitor may be faulty. I've been caught by that previously and what made it worse was it was my test monitor that had gone bad.

Disconnect all the unnecessary things and just leave the CPU, Minimum RAM and Video Card in place and see what happens when you try to start the unit. If you get a Video Signal you can them try connecting one unit at a time till it stops working. If that doesn't work you can do 1 of 2 things either try another PS or do as I would normally do pull the M'Board sit it on an Anti Static Surface and plug in a PS then connect up a Mouse Keyboard and monitor and short out the power pins to see if it's going to work before you even attempt to assemble it.

I don't like wasting time on hardware I don't know if it works properly before beginning the assembly so I just fit the bare essentials and power up to see if I get a Video Signal and then set the BIOS to what I need. I then power down and fit the M'Board to a case and then go about setting up the system properly but only after I know that it's working first.


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Forgot RAM

by w2ktechman In reply to Well a bit more detail wo ...

Often this happens if the wrong RAM is placed, or if there are chips of different technologies (DDR2300 and DDR2700), or if the chips are larger than the MB can hold, or even if they need to be placed in a sequence for the MB, or in pairs.

Video card is a big culprit, that would be a starting point along with the PS. Processor fan in the wrong plug can do this as well, even if it spins.
Also, if the second power cable (some MB's) isnt plugged in nothing works as well

Hal said most of it, I just wanted to add a tad

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Very strange symptoms

by mjd420nova In reply to MoBo Power issue

The fans most likely run on 12 volts, and so do the hard drives. But the rest run on 5 volts. I suspect the power supply. Not weak, but maybe too low.

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CMOS Reset

by TheChas In reply to MoBo Power issue

Check the CMOS reset jumper.

This is the exact symptom you get if the CMOS reset jumper is set to reset.

Many new motherboards ship with the jumper in the reset rather than the normal position.

Other things to check include the drive jumpers. Western Digital hard drives have a habit of stopping the POST process if the jumper is set to master if no slave drive is present.

Make sure that the motherboard does not have an extra 4 pin power plug. If it does, you may need a different power supply.


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Power supply

by colin_duryea In reply to CMOS Reset

The MB is a 24pin power connection and I don't quite have a TRUE 24 pin PS. The MB claims to be able to support a 20 pin (apparently it does since the fans do something) but I tried using a 20 to 24 pin adapter and still got nothing (still just the fans) Although I probably already know the answer, think I may need a true 24pin PS?

Keep the suggestions coming

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From Previous experience the 20 to 24 Pin Adaptors

by HAL 9000 Moderator In reply to Power supply

Are useless. Start off with a Known Good 24 Pin ATX PS and work from there.


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by g_gross_144 In reply to MoBo Power issue

ight sounds like it could be jumpers it could be a bad mobo and possibly a weak power supply, check the little red switch on hte back of hte power supply and make sure its set to 115. Thats what it sounds most like to me. If its on 335 then thats for the oversees power usage since they have a different system of power, if its on that then it would not be drawing enough power from the power supply. If that does not work then my other thoughs would be that maybe the computer went through a power surge and lost its video and hard drive, if this is so you can test it by using a spare hard drive. as far as video goes try to plug a nother video card into it. If all is good when you do that then well you know whats wrong.

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maybe this

by nebheprura In reply to MoBo Power issue

Actually just had similar problem with client. Thought it was motherboard, borrowed stronger power supply and oila!, it works. Not sure if you actually tried stronger p-supply, but it could make things pretty simple instead of headache.

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by colin_duryea In reply to MoBo Power issue

A lot of you have talked about video cards. Might I add that the video is onboard and not a card. Maybe that will help things along. Thank you for suggestions so far. Keep them coming.

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Well as you have On Board Video

by HAL 9000 Moderator In reply to Video

Start off with the installed RAM, then PS and CPU in that order. Also check that the monitor that you are using actually works as that can be a big nuisance when your test monitor fails.

I've seen both AMD and Intel CPU's inserted the wrong way so I would check this as another option.

Do you hear any beeps from the Case Speaker? Knowing who makes the BIOS and what the sequence of beeps is would help no end. Failing that just knowing the Make & Model of M'Board and the Beep Error Sequence will make it possible to solve the problem.


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