Computer doesn't POST, or even turn on at all

[CommandoGeek]

Hello, Tom's Community!
I currently have a problem with my custom built computer, where neither the case power button nor the motherboard reset button will turn on the system. I'd like some help identifying the malfunctioning hardware that's causing this failure.

This problem has actually occured before (1-2 weeks prior), but I only needed to turn off the PSU, wait a while, and turn it back on to get it to work again. So I didn't think much of it. I'm not sure if this is related, but I'll just state it in case it can help.

I'm sure that this isn't PSU related, because even after I bought a new identical PSU to replace the current one, the problem still persisted. I tried the paperclip trick and the PSU fans still spun. It can't be an insufficient watts problem, because I haven't changed any hardware...

I'm pretty sure this isn't a CPU or RAM related problem either, because my computer doesn't even turn on; not the fans, not the front panel LEDs - nothing. It also can't be the computer case, because I've tried taking out the motherboard, placing it on a cardboard box, then testing it again - no results.

That only leaves the motherboard. But I'm not entirely confident that the CPU and RAM aren't the culprits, and that's why I'm asking for some opinions. Are the CPU and RAM capable of preventing the computer from even POSTing?

Thanks for all your help,
John

 

[Rogue Leader]

A mobo will still power up without a CPU and ram (well at least the LEDs physically on the board will light), and with a bad CPU and ram it will definitely power up and give you some beeps form the PC speaker telling you that one or the other is FUBAR. I am reasonably sure your mob crapped out

 

[CommandoGeek]

Ah, whoops. I forgot to mention, the lights on the motherboard DO light up. But that's as far as it goes to show any sign of power entering the motherboard. Hitting the power switches on the case and motherboard do absolutely nothing.

Sorry for forgetting to point that out, and thanks for the quick response.

 

[kapitalistas]

may help recheck power cables .may help boot just only one memory stick if no DICE then check CPU for bent pins.

 

[Rogue Leader]

Ah, whoops. I forgot to mention, the lights on the motherboard DO light up. But that's as far as it goes to show any sign of power entering the motherboard. Hitting the power switches on the case and motherboard do absolutely nothing.

Sorry for forgetting to point that out, and thanks for the quick response.

Ok that changes things. it should still post but try pulling the ram out and installing only 1 stick at a time and see if it POSTS then. You may have a bad RAM stick.

Also just double check all power cables are connected including the seperate CPU power connector.

 

[CommandoGeek]

I'll do those right away. But just curious, if there's a defective CPU, should the computer still POST?

 

[CommandoGeek]

Okay, no luck with the RAM sticks. The CPU and ATX cables were also fully connected, so no problems there.

However, occasionally, the computer decides to boot up. Sometimes it lasts until you turn it back off, and other times it turns on for about a second, then loses power and goes idle again. This didn't only happen when I tested the RAM sticks; it happens at random times, with no discernable pattern.

 

[Rogue Leader]

I'll do those right away. But just curious, if there's a defective CPU, should the computer still POST?

Okay, no luck with the RAM sticks. The CPU and ATX cables were also fully connected, so no problems there.

However, occasionally, the computer decides to boot up. Sometimes it lasts until you turn it back off, and other times it turns on for about a second, then loses power and goes idle again. This didn't only happen when I tested the RAM sticks; it happens at random times, with no discernable pattern.

Yeah the computer should definitely POST even with a bad CPU, It will give you beeps from the system speaker.

A CPU going bad you would notice in having performance issues, and it would still POST, bad ram should still post as well and beep (a different sequence). Also it would do these things all the time, not randomly work fine.

When you tested the board outside the case how did you try to power it up? Did you jump out the +PW- header with a screwdriver? That would eliminate the possibility of a bad power switch in the case. I am assuming when it was out of the case all the other hardware (hard drives, video card, etc) may not have been connected, while I've never heard of a bad one preventing a PC from starting (or shutting one down regularly) i guess its possible.

Assuming all of what I just said, it sounds like your mother board is done.

 

[kapitalistas]

if you apply thermalpaste then you wanna remove cpu and check for bent pins.

 

[Rogue Leader]

if you apply thermalpaste then you wanna remove cpu and check for bent pins.

This is the only other thing maybe. In that I never asked you, did this computer run reliably and then start doing this, or is this a "new build" that started doing this after a current build? Usually a bent pin shows it self sooner and more often, but worth asking here.

 

[CommandoGeek]

This build is a little less than 2 years old, and it ran pretty reliably, apart from the occasional short lag that occurs every time I boot up the computer, but I assumed that's there for everyone, so I just ignored it.
A few days ago, I tried reseating the CPU and reapplying the thermal paste, but the problem still showed up afterwards, so that shouldn't be the problem, right?

And when I tested the motherboard outside of its case, I left ONLY the ATX connector and RAM sticks (the heatsink prevented me from taking the RAM out) plugged in, then turned the power on. I'm confident that the ATX cable is fine, since I used my spare PSU and cable as well as my original ones, and neither worked. Since my motherboard has its own built-in power switch, I used this in order to eliminate any possibilties of a case problem. Using this setup, I tried turning on my motherboard several times, turning off and back on the PSU in between the tests. My motherboard SOMETIMES booted (for seconds, minutes, then turned back off), but mostly didn't.

 

[Rogue Leader]

This build is a little less than 2 years old, and it ran pretty reliably, apart from the occasional short lag that occurs every time I boot up the computer, but I assumed that's there for everyone, so I just ignored it.
A few days ago, I tried reseating the CPU and reapplying the thermal paste, but the problem still showed up afterwards, so that shouldn't be the problem, right?

And when I tested the motherboard outside of its case, I left ONLY the ATX connector and RAM sticks (the heatsink prevented me from taking the RAM out) plugged in, then turned the power on. I'm confident that the ATX cable is fine, since I used my spare PSU and cable as well as my original ones, and neither worked. Since my motherboard has its own built-in power switch, I used this in order to eliminate any possibilties of a case problem. Using this setup, I tried turning on my motherboard several times, turning off and back on the PSU in between the tests. My motherboard SOMETIMES booted (for seconds, minutes, then turned back off), but mostly didn't.

So the problem started happening before trying to reseat the CPU and re installing the cooler if I understand you correctly? And you did that to see if it would fix the problem (but it didn't). Did that make it worse immediately or gradually?

If you wanted to be 100% sure, sticking in known a working processor and RAM stick from a working machine could confirm it, but without that luxury at this point I would still stand behind a bad motherboard.

 

[CommandoGeek]

Unfortunately, I don't have a spare processor available, so I can't test that out. And from what I know, even with no/bad CPU and RAM, the computer should still at least POST, right?
Since everything currently points to a bad motherboard, I'll go get a new one and see if that works. But I'm still curious, what is the explanation for the motherboard sometimes turning on and sometimes not? That's the most confusing bit.

 

[Rogue Leader]

Unfortunately, I don't have a spare processor available, so I can't test that out. And from what I know, even with no/bad CPU and RAM, the computer should still at least POST, right?
Since everything currently points to a bad motherboard, I'll go get a new one and see if that works. But I'm still curious, what is the explanation for the motherboard sometimes turning on and sometimes not? That's the most confusing bit.

It should POST somehow, even if it just lights up and beeps to high heaven (I'm assuming you have a PC speaker attached). You're not gonna get a BIOS screen or anything with no CPU or memory, but you will get the light up and the beeping from the speaker.

As for sometimes working and sometimes not, electronics can be finicky, could be any number of burnt components that are shorting out and then don't. Something that started to fail and just progressively got worse, etc.

 

[CommandoGeek]

Alright then. That settles it - I'll buy a new motherboard as soon as I can and update you guys if I make any progress.

Thanks a lot for your time and effort, Rogue Leader. I appreciate it

 

[Rogue Leader]

Alright then. That settles it - I'll buy a new motherboard as soon as I can and update you guys if I make any progress.

Thanks a lot for your time and effort, Rogue Leader. I appreciate it

Anytime, yes please let me know how it goes

 

[kapitalistas]

so now we know the pc was in a working state and after you remove the cpu it didnt post .the PC NOT GONNA POST WITH A BAD CPU!(95%)i didnt heard that cpu dies,probably something went wrong in process . you already check cpu for bent pins i didnt see you confirm that.you wanna check do you have spinning cpu fan,and its very helpful remove BIOS battery for minute or so and insert it back.

 

[CommandoGeek]

Can confirm, was the motherboard. Now everything works fine! It even fixed a few other problems that I previously thought were unrelated, like the temporary lag I used to get at every startup. Only problem was, I had to reinstall windows, since the mouse and keyboard drivers for this motherboard are different from the old one, thus leading to the inability to use ANY I/O devices.

 

[Rogue Leader]

Can confirm, was the motherboard. Now everything works fine! It even fixed a few other problems that I previously thought were unrelated, like the temporary lag I used to get at every startup. Only problem was, I had to reinstall windows, since the mouse and keyboard drivers for this motherboard are different from the old one, thus leading to the inability to use ANY I/O devices.

Awesome! Yes you always need to re-install windows with a new mobo I'm surprised it went far enough to start up, sorry should have mentioned that. Glad it worked out!

 

[kapitalistas]

you dont need reinstall Windows if you change motherboard. its two separate things.

 

[CommandoGeek]

you dont need reinstall Windows if you change motherboard. its two separate things.

Sorry if I didn't clarify, but I was using an OEM version of Windows 7, so when I switched motherboards, the computer didn't like it and rejected the drivers from my old installation of Windows. Sucks, I know 🙁

 

[Rogue Leader]

you dont need reinstall Windows if you change motherboard. its two separate things.

Wrong, you absolutely do need to re-install windows. Its not 2 separate things, from Windows 7 on it pairs itself to the hardware of the motherboard. At a minimum it rejects you because it ties the cd key to the new board, but 9 times out of 10 it won't even boot.