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Pc not posting - possible dead motherboard or cpu


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#1 Varcoe88

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Posted 06 July 2017 - 01:03 PM

Hi All

I've been trying to upgrade my cpu from a 2nd gen core i3 to a 3rd gen core i5. Out of sheer stupidity I didn't realise that I would need to flash the bios to allow my motherboard to use a 3rd gen processor. I found this out after getting 4 long beeps from the motherboard with the i5 installed. I have since reinstalled my i3 to try and download the bios update and run into problems where the pc won't post. The cpu and system fans run and light up but no error beeps and no display on the monitor. It will now run one of 3 ways. It will carry on running with fans and lights with no display or beeps, run for around 20 to 30 seconds before shutting down and restarting or shut down and restart after 5 seconds.

My specs are:

msi h61m e23 b3
Core i3 2120
8gb ddr3
gtx 660
Corsair cx650m (brand new)

So far I've taken the following steps:

Checked all power connections including 4 pin cpu connector.
Made sure ram and graphics card are all seated correctly.
Checked for bent pins in cpu socket.
Reset cmos.
Tried each ram module in one slot then the other.
Checked and replaced the power supply unit.
As I've had the motherboard out to replace cpu I've breadboarded the system with just cpu and cooler and ram with the same results. Removed ram to verify neither module are causing the problem.

If I try to reinstall the 3rd gen i5 processor I still get the continuous 4 long beeps before it shuts down but nothing at all with 2nd gen i3. So I'm guessing dead motherboard or cpu. Any help greatly appreciated.

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#2 jonuk76

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Posted 06 July 2017 - 01:45 PM

The power needs to be disconnected when you clear the CMOS.  If it was, if you reset the CMOS by shorting jumper pins, try instead removing the CMOS battery for a good period (20 minutes should be more than enough).

 

Have another look at the CPU socket pins using a flashlight, and looking at them from different angles. Even one slightly bent pin, if it's a crucial one can stop it working, and it doesn't take much to bend them.  A few slightly bent may be repairable if you're careful.

 

Other than that it sounds like you've tried all the things I would. The chances of it being the CPU are less than a motherboard fault.  The chances of it being 2 CPU's are even less still.  The trouble is new LGA1155 motherboards are not widely available now, so you might be looking at used parts if you do decide to replace.


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#3 Varcoe88

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Posted 06 July 2017 - 03:19 PM

I've had another close look at the cpu socket under a good light and still don't see any bent pins.

The issue Im having in determining between the motherboard and cpu is that the i3 is supported by the bios but the i5 isn't without the bios being flashed. But it is only with the i5 that I get 4 long beeps. Other than that whichever cp u is installed the outcome is the same. No post and restart after a short time.

I do have a used motherboard on the way although this will also need a bios update as my stupidity dictates I make the same mistake twice before learning my lesson. I also have a used 2nd gen i3 processor coming in case it is the cpu that is fried.

#4 technonymous

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Posted 06 July 2017 - 03:53 PM

I would have to concur with the post above. Something is missed. A few things to consider...

 

-CPU not mounted correctly (bent pin)

-Silver thermal compound shorting out the cpu

-Fan power not plugged in (Warning Beeps adn shutdown indicating cpu fan not connected at all)

-PSU 4 pin connector not connected to the motherboard.

-BIOS settings are messed up and the CMOS chip needs a reset by pulling the battery or moving the jumper. Be sure to pull power plug from the wall before reset.

-Worst case CPU and or both Motherboard/CPU is done fried. Without a Heatsink mounted correctly a CPU will burn itself out almost instantly.



#5 Varcoe88

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Posted 06 July 2017 - 04:04 PM

I'm fairly confident I've checked all these things.

Cpu is mounted properly as far as I can tell. Im 99% certain there are no bent pins. If there were then I'd assume neither cpu would give warning beeps. The unsupported 3rd gen i5 does but not the supported 2nd gen i3.

There is no thermal paste on the underside of the cpu - only on the top.

The cup fan is plugged in and spins when the system is turned on. I'm fairly certain the warning beeps from the i5 are due to it not being supported by the bios.

Psu 4 pin connector is definitely connected up the motherboard.

Have pulled the CMOS battery for over 20 minutes as suggested with the power disconnected and still no change.

Heatsink is definitely mounted correctly, tight fitting and the fan spins up.

If the warning beeps Im getting from the i5 are in fact because the bios does not support it, could this indicate the motherboard is actually fine and it's the i3 cpu that is at fault as I get nothing with it installed?

#6 technonymous

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Posted 06 July 2017 - 04:46 PM

Check that the memory is seated properly. Go over all the wires again. Main harness etc. If it doesn't post after putting in the i3 and a reset then I am afraid you have blown something out. Time to take it to the shop they can test both. A bad cpu can kill a new mobo and vice versa.



#7 Varcoe88

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Posted 06 July 2017 - 05:15 PM

Memory is definitely seated properly. I've tried one module at a time in each slot and tried without any memory at all. Still no warning beeps under any circumstances other than with the i5 installed.

I've gone over the wiring so many times I am 100% certain it is fine.

I'll wait for my replacement parts to arrive and flash the bios on the new motherboard to enable the i5 to work then I will test the replacement i3 on my old motherboard and determine which was at fault.

Thanks for all suggestions.

#8 jonuk76

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Posted 06 July 2017 - 10:31 PM

Good luck.  With all those extra parts you should be certain to get something working at the end of it!


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#9 Varcoe88

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Posted 12 July 2017 - 02:47 PM

Just to update, turns out it was the motherboard at fault. New motherboard arrived and the i3 worked fine. Didn't even require a bios update to allow the i5 to work as it had already been done.

#10 jonuk76

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Posted 13 July 2017 - 11:17 PM

Great.  Glad it appears to be sorted :)


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