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Motherboard or CPU?

Yesterday my son's machine refused to boot.  Case fans will spin for a few seconds, then nothing.   CPU fan does not start.   Power Supply seemed to check out ok, although PS tester had no light on the -5 volt.  (All others steady green)    
Removed HD 7870 video card and connected to onboard DVI port.  Still no luck.  Any suggestions?   Hate like heck to replace mobo or cpu, cost is definitely an issue.   Thanks in advance.
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t6bill
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t6bill
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3 Solutions
 
t6billAuthor Commented:
Sorry, forgot to mention I did reseat the RAM, no luck there, either.
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JohnBusiness Consultant (Owner)Commented:
The -5volt rail may not be used. It depends on the design of the computer.

Remove any peripherals (CD player for example).

Remove both memory modules (or all memory modules and lay them out so you know where they came from. Try one module and see if it boots. Then the next and so on. Is it just memory?

Otherwise it is the motherboard / CPU and I would assume the CPU before motherboard. But that is just an opinion.

How old is the machine, how much memory, how much disk, and what operating system?

Do you have a make and model for the computer.
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web_trackerComputer Service TechnicianCommented:
The power supply still could be affected as the cheap power supply testers that only have the leds are not very affective in showing  power supply failure. These power supply testers only tell you that there is specific voltages present, it does not give any information to amperage. The only way to know if the power supply is affected is by trying to boot up the system with another power supply. The power supply is usually the first component to fail when there is a power spike.  It is hard to say if the symptoms that you are experiencing is from a bad mobo, cpu or power supply, but in my experience the power supply is the first affected, unless you notice that there are bad capacitors on the motherboard. Swollen or leaking capacitors on the mobo could definitely cause the systems you are experiencing, but if they look okay consider swapping out the power supply.
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nobusCommented:
first - what system are we talking about?  some specs on model, or cpu, ram

you can use my minimum setup guide for finding the bad part :  http://www.experts-exchange.com/Hardware/Components/Motherboards/A_1945.html                  (Short-overview-of-how-to-troubleshoot-bad-hardware-when-a-pc-does-not-post)

but that leaves you with motherboard or cpu -  which you can only find out by replacing one of them.

if the system has had no prior problems (overheating) chances are 95% motherboard
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Gary CaseRetiredCommented:
First thing I'd do is see if it boots okay with a different power supply (If you don't have a spare, try the one from your PC).    Do that with minimal "stuff" connected (i.e. use the onboard video and not the dedicated card).

If the symptoms don't change, I agree the most likely culprit is the motherboard.   Since your tag indicates this is a Socket 1155 system, it's certainly new enough to be worth repairing.    It's also possible it's a CPU issue, but I'd rate that far less likely than the motherboard.

One other thing:   If the system was opened for any internal work (blowing out the dust; adding a component; etc.) then be sure that this isn't just a loose or missing cable.
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t6billAuthor Commented:
More info:   Motherboard is Gigabyte GA-Z77X-UP4.   CPU is an i5 socket 1155.  Everything is in a Cooler Master HAF XB.  Sorry don't remember particular i5 for the 1155 socket.  Motherboard OR CPU is a heartbreaker, both are pretty expensive, but I believe it is one of the two.   Used Intel's stock cpu cooler, perhaps shouldn't have done.  Thanks for all the suggestions.   SilentPro 1000w power supply.  

I know we don't have a definitive diagnosis yet, but...if we have to replace either mobo or cpu, will probably do both and go with 1150 socket.  Big question:   Is 1155 a dead upgrade path?

System is home-built and only about 1 year old.
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JohnBusiness Consultant (Owner)Commented:
System is home-built and only about 1 year old.  <-- You might try removing the CPU and replacing the thermal compound. That is an easy thing to try before replacing the board.
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nobusCommented:
did you try the minimum set up yet?
also - the ps tester only shows the voltages are ok - nearly without load.
if you have access tyo another PS for testing, try that too

another option is to turn it in at a shop for diagnosis
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web_trackerComputer Service TechnicianCommented:
Previous experts including myself have suggested trying out another power supply, if you have not already done so please do so, it is much cheaper to replace the powersupply than to replace the cpu and mobo. If the problem is with the powersupply replacing the mobo is not going to solve your problem.  The power supply tester you used that have only little leds is not affective in testing your system with a load, they only tell you you have the correct voltage but not the ampherage.
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Gary CaseRetiredCommented:
Agree (as I also said earlier) that you should try a different power supply before anything else.    It's not likely that's the issue, but if it is you want to know NOW before you start buying a whole new setup.     I assume you have another system you can try the supply from ... you don't have to mount it in the case; nor do you even have to connect all the extra "stuff" (hard drives, optical drives, etc.).    Just connect the ATX connector and the 8-pin  auxiliary CPU power connector and see if you get to the BIOS.     If so, then shut down and connect your boot drive and see if it then boots okay.

If you're going to buy both a motherboard & CPU I agree you should use Haswell components.    HOWEVER ... a good Ivy Bridge system has very nearly the same performance as a Haswell, so you really don't need to replace them both.   Note that there's only 5-10% difference in CPU performance between the top-of-the-line Ivy Bridge CPU and top-of-the-line Haswell CPU except for the improved graphics ... and you're not using the built-in graphics anyway.

As for whether or not it may be the CPU ... did you overclock this system?    The stock Intel cooler is just fine for running at the specified parameters; but if you were significantly overclocking the CPU without additional cooling, that increases the likelihood that the issue is the CPU and not the motherboard.     But if you weren't overclocking, then this definitely sounds like a motherboard issue if it's not simply out-of-spec power from the power supply.
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t6billAuthor Commented:
No, system has never been overclocked.  Tried another power supply and exact same symptoms.  Power supply fan turns for a few seconds.  CPU fan turns for less than a second.  Repeats.
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JohnBusiness Consultant (Owner)Commented:
That is why I asked you to consider reseating the CPU with new thermal compound. That may not be the issue, but it is cheaper to try than a new motherboard.
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t6billAuthor Commented:
Might have some arctic silver laying around, will try first.  Thanks!
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Gary CaseRetiredCommented:
Different power supply but same symptoms certainly makes it unlikely the issue is power.

Your symptoms also aren't what I'd expect to see with degraded thermal compound --  if that was the case, the system should still boot, but would rapidly overheat and do a thermal shutdown.    That would NOT happen so quickly that you didn't at least get a BIOS screen ... and it'd be more likely it would boot all the way to Windows before it hit thermal shutdown.    Won't hurt to do what John suggested -- it's just very unlikely that's the issue.  [It's basically free to try, however, since you'll need to buy some thermal compound anyway to move the CPU to a new motherboard]

At this point, it's almost certainly the motherboard, with a small chance it's the CPU.     The only other possibility I can think of is that the CPU fan has failed => many BIOS's will automatically shut down if the CPU fan isn't spinning ... although I'd expect a quick BIOS display and error message before that happened, so I don't think that's the issue.

Fortunately, you can get an excellent Z77-based motherboard to replace your defective one for under $90:  http://www.newegg.com/Product/Product.aspx?Item=N82E16813131965
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nobusCommented:
that's what i posted before :  if the system has had no prior problems (overheating) chances are 95% motherboard

did you try the minimum setup ?  you did not answer  that
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t6billAuthor Commented:
Yes, I disconnected all drives with no difference.   Removed RAM, etc.
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nobusCommented:
then as you supposed, it leaves you with the choice between mobo and cpu
you can clean the heatpaste, and renew it, while removing reseating the cpu.
if it does not help, i would start with the mobo -  if it is worth replacing
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t6billAuthor Commented:
OK!  Sorry for the delay.   It WAS the motherboard.  Old CPU inserted into new mobo = success.   Thanks for all who waded into the fray.  This comment:   (" it's almost certainly the motherboard, with a small chance it's the CPU. ")  is the one that determined why I awarded the points.  It certainly seems the most spot-on.

But thanks to ALL who offered their trouble-shooting suggestions!
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