Lenovo Legion 5 high fan spin turns off after 34 seconds

[twonk9098]

Hi all,

I have a Lenovo Legion 5 with a Ryzen 7 series CPU and RTX 3070 GPU. My issue is that it turns on and all seems fine except after a few seconds the fans spin up high and the laptop turns off after 34 seconds.
I can get into bios and can even boot and login to Windows however after 34 seconds no matter if Im at the bios screen or booted into Windows it will just turn off.

I have managed to run HWmonitor and the temperatures of the CPU and GPU are fine, I can also touch the heatsync which is warm but not hot.

I have tried a few new bios but exactly the same thing.

If I remove US134 which is a thermal sensor then the laptop stays on for 65 seconds before turning off, putting it back it shuts off at 34 seconds again.

I read on a forum that it maybe the MUX switch which if I disable discrete graphics in the BIOS does not change anything. I could remove the MUX chip but I'm not sure what will happen or what it will prove.

Any ideas?

Many thanks

[barakuda123]

Hi got exactly two same motherboards with this issue one had short on 3v ldo and 3vs line after replacing kbc edp mux and usb c pd controler board start but shuts off after 20-30sec , second same board cpu was dead ( No cristal oscilation) replaced cpu and same story laptop starts shows pictures can enter bios but again shutdown after about 30sec....
Did you menage to sort this out?

[rewx5]

Hi guys, have you figured this one out? I'm having the same issue!

[twonk9098]

Hi guys, I finally figured it out. My issue was US1 which is a F75303M. It's a temp sensor chip for the CPU.
Ordered mine from Aliexpress and fitted. Laptop is perfect now.
Hope this helps.

[rewx5]

Hi guys, I finally figured it out. My issue was US1 which is a F75303M. It's a temp sensor chip for the CPU.
Ordered mine from Aliexpress and fitted. Laptop is perfect now.
Hope this helps.

Awesome! How did you find out? Mine started doing this after I have removed the mosfets for the GPU and VRAM as the discrete gpu had a shorted mosfet.

[twonk9098]

Hi, I removed US1 because it is a sensor IC for the CPU according to the schematics. I noticed upon removal the laptop would stay on for 64 seconds instead of the 34 seconds with it installed. This made me think there was an issue with it therefore replaced it. After replacing it, the laptop worked totally fine. Tested under full load to and the temps got up to 89 degrees at a push.

[twonk9098]

The other thermal sensor on the board is U134, I believe this one is for the GPU.

[denyslykh]

Dear friends good day. Care to help me please, has same issue exactly after just changes ssd. Service guys told me that GPU chip is dead. Laptop is switch on for abt 30 sec, fan runs on max speed but after switch off. For this short 35 sec I can go into Bios and Windows whatever but for 35 sec. Device manager didn't find rtx 3070 even with some errors massages.
Please help me what to check. How is possible to make dead gpu, laptop not used for gaming.

[twonk9098]

My issue was caused by changing the SSD without disconnecting the battery.

This caused an issue with US1.
The laptop would work fine for 34 seconds before turning off however the fans ran high.

To prove, remove US1 and turn the laptop on. Ensure you have the heatsync back in place.
Check how long the laptop stays on for, mine was just over 60 seconds. If this is the case, replace US1.

Regards

[denyslykh]

Many thanks for answer, in my case same situation, i am change ssd without disconnecting battery. Just for clarification do you have any missing device, because in my case I has missing rtx 3070 in device manager and guys from service tell me that gpu chip is out of order and should be replaced. That's why I am asking if you have missing device.

[denyslykh]

Also AMD video dissappear from device management. Only "Microsoft Srandard Dispaly" showing in video adapter column. Reinstall driver for AMD I can't. Not enough time. Someone can explain even rtx 3070 out of oder the laptop should continue working on internal amd graphics correct ?

[twonk9098]

My RTX 3070 showed an error in device manager (exclamation mark). I am not sure about the AMD graphics.
I will say though that removing US1 gave me more time, it increased from 34 seconds to about 103 seconds. Just remove US1 and if you get the extra time then replace the IC. They about $8 from Aliexpress.

I will also say that the coils on the VM for GPU gave very low readings in diode mode on my multimeter. Around 0.01 ohm if I remember correctly however this is normal for this device.

I hope this helps.

Regards

[twonk9098]

Also bare in mind, the AMD graphics is from the CPU and not the GPU. The RTX is from the GPU. It makes little sense for them both to fail especially when your CPU is working as it boots to bios and further.

[twonk9098]

Oh and as I think about it, some may say it's the PCH however being AMD, there is no PCH.
Honestly, just remove that US1 and boot it up to see if you get extended time, if so, replace it.