Mobo or something wrong, please help

ChiYoungKC · January 29, 2019

Hello, I'm new to this forum and this is my first post and I though this might be the right place to ask for this problem im having

This week i got to help with someones PC that at first seems to had a dead CPU and replaced it with one i had lying aroud at home

Oh yeah this PC specs are,

ASUS Maximus Extreme mobo

had a Q9450 775socket cpu that died and i just had a e7300 (pretty basic) but does the job.

4x2gb ddr3 ram

GPU is HD 5870 that somehow it worked at start then died and gave only blue screen flickering at times and the next day it worked again.

2 sound cards that I dont think matter for this

and 3 hdd 2x80gbs and one 500gb

Nowdays its only used to download stuff and view series/movies.

Story is, PC came saying checksum didnt match, troubleshooted and ended up changing cpu, then it started working, even got to boot into windows 10 once.

turned off, then i had the problem with the graphics card were it was working fine one moment and the next was dead, after a day i tried again and was working fine.

so after i had image back the PC wouldn't boot into the HDD, saying select boot device...

I though at first it was a problem with the windows files, and tried with a Windows installation disc, via cmd and automatic repair, all those cmds in the internet, set partitions active, bootrec, etc

So i took the hard drives out and put them in my PC and backed up everything and then did a clean install of windows from a usb, downloaded win10 1809 from the media creation tool.

windows worked fine in my PC, but as soon as I put it back in the problematic PC it wont boot and show the same message again. OFC boot order is in the hard drive, disabled the rest
by this point i have clear that, CPU, ram, graphics, hard drives are all fine.

Could it be the mobo? Oh, HDD is recognized at post and bios, can boot into external CD/DVD reader but cant boot into a usb

I've ran out of ideas apart from reinstalling the mobo bios but already loaded defaults many times.

What do you guys think?

Thank you if you read that all.