Question Help - New PC build does not post

May 22, 2020
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Hi everyone

I'm having problems with my first build ever: when I try to switch it on I can hear the AIO pump, fans and PSU fan spin but they immediately turn off after less than a second (like a short circuit).
components:
mobo ASUS ROG STRIX B450-F
processor Ryzen 5 3600
RAM Kingston HyperX predator 2x8GB 3000
AIO Corsair H55
Graphic RTX 2070 super
SSD Samsung 970EVOplus 500GB
PSU Corsair CX750M
every single component is brand new, except for the PSU that I bought from Amazon warehouse.
tests I already ran:
I have checked the cables different times. I have reseated every component different times in every slot available. even if the standoffs have have been mounted I have placed the mobo on its box. I have reset the CMOS both with a jumper on the pins and by takyng off the battery.

I'm starting to think that this may be a PSU issue, but I can tell for sure the mobo is powered on because of a RGB LED on the IO shield. I don't have any other component to test.
 
Jul 15, 2019
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Sounds like a PSU issue, Sounds like your pc shuts itself down when it realises it's not recieving enough power to boot properly, especially if you cannot see a BIOS screen, swap out the psu that would be the first test, return it to amazon if need be

other issues might be compatibility between motherboard and cpu but i doubt it, i think ram incompatability can also cause a no post scenario aswell but they are unlikely, double checking this is worth the time though

can you hear any other noises that are unexpected when you switch on the system? popping/crackling from psu specifically
do you have any debug led's on the motherboard? do any of them light up?
any post beeps if you have a motherboard speaker?
 
May 22, 2020
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Sounds like a PSU issue, Sounds like your pc shuts itself down when it realises it's not recieving enough power to boot properly, especially if you cannot see a BIOS screen, swap out the psu that would be the first test, return it to amazon if need be

other issues might be compatibility between motherboard and cpu but i doubt it, i think ram incompatability can also cause a no post scenario aswell but they are unlikely, double checking this is worth the time though

can you hear any other noises that are unexpected when you switch on the system? popping/crackling from psu specifically
do you have any debug led's on the motherboard? do any of them light up?
any post beeps if you have a motherboard speaker?
I checked every component compatibility before buying them.
I can't hear any noise from the PSU.
not sure if the LED on the IO shield is for debug, but it lighs up as soon as I hit the power switch on the PSU and never shut down untill I hit that again.
unfortunately the mobo didn't come with a speaker.
 
Jul 15, 2019
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does the psu fan spin up?
ahh the led logo on the heatsink? yea that is aesthetics not for debugging


Says on the manufacturers website that you have debug led's, pop off the side panel and look to the top right of the motherboard, that atleast is where mine are, you should see about 4 of them in a row
BOOT
VGA
DRAM
CPU
each one will be marked have a light and when powered on it should indicate where the issue is, seems like they will be pretty easy to spot, if none of them show up then the motherboard is not being powered properly, as the BOOT will always flash atleast briefly on startup
 
May 22, 2020
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Update:

I actually had a brand new PSU (Corsair CX650M) I wanted to give back because I found that 750 at a much better deal, but it looks like I'm giving back the 750 because with the new 650 it switches on!
now I can see the debug LEDs light up: first the DRAM (yellow light), second the CPU (red light!), third the VGA (white light) and last the BOOT (green light). they light up one at a time, never simultaneously.
 
Jul 15, 2019
97
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Update:

I actually had a brand new PSU (Corsair CX650M) I wanted to give back because I found that 750 at a much better deal, but it looks like I'm giving back the 750 because with the new 650 it switches on!
now I can see the debug LEDs light up: first the DRAM (yellow light), second the CPU (red light!), third the VGA (white light) and last the BOOT (green light). they light up one at a time, never simultaneously.
DRAM is the power distribution for the motherboard
CPU gets powered by this first
VGA is either onboard graphics for the motherboard or CPU and GPU
BOOT is when it tries to contact the HDD or SSD for windows

Can you see the BIOS and access it, it might be that then bootdrive is disconnected or not listed as the first drive
 
May 22, 2020
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DRAM is the power distribution for the motherboard
CPU gets powered by this first
VGA is either onboard graphics for the motherboard or CPU and GPU
BOOT is when it tries to contact the HDD or SSD for windows

Can you see the BIOS and access it, it might be that then bootdrive is disconnected or not listed as the first drive
absolutely nothing shows up on the monitor. I still have to install windows via USB drive but I can't access the BIOS.

I'm using an HDMI port (my monitor doesn't have DP) and I know that, sometimes, it may not work because it needs drivers that are not always pre-intalled. could this be the problem (I don't think because the BOOT LED wouldn't stay on if this was the only problem, I guess).
 
Jul 15, 2019
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Be sure all the new connections from the psu are seated properly

Try removing the graphics card and plug the monitor straight into the motherboard IO, then the feed can only come from the motherboard itself and be sure that the monitor is set correctly, some will auto detect and switch to a new input and some will present you with a black screen until you switch to hdmi, display port etc and is easily overlooked, if this presents the BIOS then that is a good sign, if it does not there may be another issue

Also is the machine still powering itself down after a second? Is it staying on? or is it stuck in a boot cycle, where it keeps restarting itself
 
May 22, 2020
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Be sure all the new connections from the psu are seated properly

Try removing the graphics card and plug the monitor straight into the motherboard IO, then the feed can only come from the motherboard itself and be sure that the monitor is set correctly, some will auto detect and switch to a new input and some will present you with a black screen until you switch to hdmi, display port etc and is easily overlooked, if this presents the BIOS then that is a good sign, if it does not there may be another issue

ok I've managed to access the BIOS, but I had to plug in a HDD from another PC because it's not detecting the NVMe M.2 SSD.
also I have 3000Mh RAM but the memory frequency seems to be 2400, any idea why?
 

FoxVoxDK

Honorable
Jul 5, 2014
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The NVMe slots can be a bit finicky when trying to seat them properly, try and re-seat it.

For your RAM speed, locate XMP settings and select the one that matches your advertised speeds.
 
Jul 15, 2019
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ok I've managed to access the BIOS, but I had to plug in a HDD from another PC because it's not detecting the NVMe M.2 SSD.
also I have 3000Mh RAM but the memory frequency seems to be 2400, any idea why?
I had an issue with my m.2 slots, nvme drives and sata drives are different so be sure you have you have it in the right slot, try it in the other slot if you have one

My sn550 wd blue would work fine in either socket but the wd blue 3d nand m.2 i bought would only work in a gen3x4 slot, so i had to swap them over and lose performance on the faster drive, so bare in mind they are not all compatible
 

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