screen shows nothing, MSI debug LED, need help

[CRRogue]

So I picked this components for my parents' new pc:

Intel core i3-7100

MSI Z270m Mortar
Corsair ValueSelect DDR4 8gb 2133

psu tacens mars gaming mp500

 

I looked for almost all of them on pcpartpicker.com, and it says that all of them are compatible (but the psu, which isn't at their selection). I've built it and it apparently turns on, but the screen shows nothing and the "EZ debug LEDs" for the CPU and the DRAM are constantly flickering, changing between them (CPU turns on, then off, then DRAM turns on, then off and repeat). I've tried unplugging and plugging again everything, putting the RAM in all of the sockets, all the video outputs (it doesn't have graphics card). I've tried to reset the CMOS, and to breadboard it, with the same result, even turning it on while it's over the motherboard's box.

I don't know what else can I do, because theoretically everything should work.

Thanks

[Zando_]

15 minutes ago, CRRogue said:

So I picked this components for my parents' new pc:

Intel core i3-7100

MSI Z270m Mortar
Corsair ValueSelect DDR4 8gb 2133

psu tacens mars gaming mp500

 

I looked for almost all of them on pcpartpicker.com, and it says that all of them are compatible (but the psu, which isn't at their selection). I've built it and it apparently turns on, but the screen shows nothing and the "EZ debug LEDs" for the CPU and the DRAM are constantly flickering, changing between them (CPU turns on, then off, then DRAM turns on, then off and repeat). I've tried unplugging and plugging again everything, putting the RAM in all of the sockets, all the video outputs (it doesn't have graphics card). I've tried to reset the CMOS, and to breadboard it, with the same result, even turning it on while it's over the motherboard's box.

I don't know what else can I do, because theoretically everything should work.

Thanks

PCPartPicker list please? And you didn't need to get a Z chipset mobo for a non-K processor. 

[CRRogue]

3 minutes ago, Zando Bob said:

PCPartPicker list please? And you didn't need to get a Z chipset mobo for a non-K processor. 

https://es.pcpartpicker.com/list/jLyczM

[Zando_]

1 minute ago, CRRogue said:

https://es.pcpartpicker.com/list/jLyczM

BIOS update? And what PSU are you using? And the CPU heatsink and thermal paste are applied correctly?

[CRRogue]

1 minute ago, Zando Bob said:

BIOS update? And what PSU are you using? And the CPU heatsink and thermal paste are applied correctly?

based on MSI's compatibility list it shouldn't need a BIOS update. PSU manufacturer webpage. Both of them, i've took it out and in a couple of times, the thermal paste is the same and it's applied the same way that i did on my rig.