ASUS X751B : only launch bios and really hot!

[disorder]

hello i need some advice to try to repair an asus X751B laptop

history ; 2 years old. out of warranty since may 2020
sudenly during use, the wifi became lost, unable to dectect wifi card
the customer push plane button and then shut it off.

since the laptop boot only on bios, the hard drive is detected but unable to boot on windows 10
at the same time, the laptop became really hot, 76° in the bios, fan spin at full speed and battery drain ++

try reset bios : the same

on inspection, the motherboard looks great. i try boot without wificard, keyboard,trackpad, screen : the same

the most hot region is the power supply under the CPU, the coils are really really hot ++++

i'm not specialist and maybe wrong but it seems like too power go trough them.
can't explain why it doesn't lauch win10.

did someone encounter such a weird problem ?

thank you all

[caspian]

Re: ASUS X751B : only launch bios and really hot!

how long does it takes that the coils or the CPU become really hot?
how much is their maximum hot temperature?
does it boot from a USB bootable memory or a CD-ROM?
measure resistance on the coil when the laptop is off.

[disorder]

Re: ASUS X751B : only launch bios and really hot!

hello some news and thanx for help
the coil becomes hot after asus logo appeared, progressively.
the temperature is indicate in bios near 76°
i have tried boot from usb and it works : only if hdd is disconnected, but it is hot too.
not have new hdd try install. it's the third time the hdd dies on this laptop in 2 years... seems strange
i will try new w10 install to see.

thank you

[caspian]

Re: ASUS X751B : only launch bios and really hot!

For now, avoid connecting HDD to this laptop. Boot the laptop using a Live Windows/Linux DVD with graphics and then, see how the laptop works. Specifically, considering temperature and playing videos. Then, you should measure voltages on the mainboard. Specifically, 5v and 3.3v.

[Duranitron]

Re: ASUS X751B : only launch bios and really hot!

have you checked all the voltage rails.. 19v 3.3v 5v 1.35v for ddr3L memory try to replace the heating coil and also the 2 mosfet n and p channel connected to the heating coil. also check the voltage powering the hard drive..

[disorder]

Re: ASUS X751B : only launch bios and really hot!

hello
thank you for help
for now, i have not try boot the laptop with a live windows usb cause need at least 32go
so i will bring some news later

[Duranitron]

Re: ASUS X751B : only launch bios and really hot!

if the processor power is taking much heat.. try to test all the caps around the processor for short or partial short..the system will shut down if too much current is drawn by the processor or the gpu.. try that... gud luck..

[disorder]

Re: ASUS X751B : only launch bios and really hot!

hello
some news, bad news
i've tried launch ubuntu from usb disk : the laptop worked normaly : boot on usb drive, launch ubuntu and NOT hot, fan speed normal, all worked properly

i've tried another hard drive : not recognized as boot system although windows7 is installed on it, and laptop HOT too this time.

so when :
-usb drive is plugged with os : not hot and works
_hdd drive is plugged : boot only in bios and hot
-hdd drive unplugged : boot in bios and hot

so i suppose that when usb drive is plug in and hdd not connected, it doesn't try to drive the hdd.
so could my issue comes from hdd driver issue ?

thank you

[piernov]

Re: ASUS X751B : only launch bios and really hot!

Advanced power management features are not enabled inside BIOS so it may be normal that it's getting hotter.
BIOS is most likely configured to boot in UEFI mode by default, so if you plug an HDD with an OS installed in BIOS mode it won't boot from it. Make sure you have CSM/Legacy boot in this case. Or better, install fresh OS in UEFI mode on a known good HDD (or rather SSD).
You can confirm a known good HDD is accessible when booted in an Ubuntu Live USB.