Question Pc turns on and off repeatedly.

Apr 8, 2020
7
1
15
0
Hello,
Started building a pc for my sister yesterday with the following specs:

CPU: i5 7400 [re-used from old build]
MOBO: Msi z170a [re-used from old build]
RAM: 4x4gb ddr4 [re-used from old build]
GPU: Gigabyte GTX 1650
1x Sata SSD
1x Sata HDD
PSU: Corsair CV550

The parts that are being re-used all worked before and even worked when i tested this build outside the case. Put it all in the case and suddenly the pc wouldnt turn on anymore. I turn it on, all the fans spin, the mobo lights up, not a second later it shuts down again and repeats that loop after 1-2 seconds.

Things i've tried:
Tested with my own PSU -> Same problem.
Swapped RAM around to all slots -> same problem, also occurs without any RAM installed.
Jumped JBAT1 for a cmos reset -> didnt work.
Pulled cmos battery out for a good 30 minutes -> didnt work
Checked for bent pins -> Pins look fine.
Checked for burned VRM's -> VRM's look normal
Took everything out and built it up again outside the case -> still the same problem.

Whats interesting is that when you pull the CPU 8 pin and leave the 24pin it actually does start up, as in, the fans stay on and the mobo stays lit up.

Does anyone know whats going on? I dont have another intel cpu or lga1511 board laying around to test cpu or board.

Thanks in advance.
 
Apr 8, 2020
7
1
15
0
What BIOS version does your motherboard have? It needs at least version "7976v1H" to support the i5 7400 CPU.
I dont know exactly what BIOS is on there, When i got the board originally it needed a bios update. got that done in the store and after it worked good for 3 years until i switched to ryzen last summer. Now im trying to reuse the board with the same cpu and same RAM but this issue came up
 
Apr 8, 2020
7
1
15
0
Have you tried booting with no drives connected to see if you can get into the BIOS?
It gets nowhere close to that. everything powers off within a second. With the entire system turned off, with all but CPU and RAM disconnected. even with no RAM. The only way i can get it to actually not power off is when you disconnect the CPU power cable. But obviously you are not gonna get very far without a CPU.
 
It gets nowhere close to that. everything powers off within a second. With the entire system turned off, with all but CPU and RAM disconnected. even with no RAM. The only way i can get it to actually not power off is when you disconnect the CPU power cable. But obviously you are not gonna get very far without a CPU.
You have a Slow Mode Booting Switch located at the bottom of your motherboard labeled "SLOW_1", is it set to Enabled or Normal (Disabled)? Have you tried both settings?
 

Plumms

Honorable
Oct 10, 2014
10
2
10,515
0
Hello,
Started building a pc for my sister yesterday with the following specs:

CPU: i5 7400 [re-used from old build]
MOBO: Msi z170a [re-used from old build]
RAM: 4x4gb ddr4 [re-used from old build]
GPU: Gigabyte GTX 1650
1x Sata SSD
1x Sata HDD
PSU: Corsair CV550

The parts that are being re-used all worked before and even worked when i tested this build outside the case. Put it all in the case and suddenly the pc wouldnt turn on anymore. I turn it on, all the fans spin, the mobo lights up, not a second later it shuts down again and repeats that loop after 1-2 seconds.

Things i've tried:
Tested with my own PSU -> Same problem.
Swapped RAM around to all slots -> same problem, also occurs without any RAM installed.
Jumped JBAT1 for a cmos reset -> didnt work.
Pulled cmos battery out for a good 30 minutes -> didnt work
Checked for bent pins -> Pins look fine.
Checked for burned VRM's -> VRM's look normal
Took everything out and built it up again outside the case -> still the same problem.

Whats interesting is that when you pull the CPU 8 pin and leave the 24pin it actually does start up, as in, the fans stay on and the mobo stays lit up.

Does anyone know whats going on? I dont have another intel cpu or lga1511 board laying around to test cpu or board.

Thanks in advance.
To me this sounds like you need to reseat the Processor. Just a hunch though. Possible that you need to ensure standoffs are installed properly too so that nothing is being shorted near the CPU.
 
Apr 8, 2020
7
1
15
0
To me this sounds like you need to reseat the Processor. Just a hunch though. Possible that you need to ensure standoffs are installed properly too so that nothing is being shorted near the CPU.
Ye i already tried reseating it once, no good. It also doesnt work on a cardboard box so I dont see how shorting is causing the issue either. Will try reseating the CPU again tonight although i doubt its gonna work.
 
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