⟐ Answered March 17, 2025 at 2:29 MST

I have a Lenovo ThinkPad T460 (board is BT462 NM-A581 Rev:3).

Whilst the laptop was powered on (plain web browsing, nothing fancy) Windows crashed with a blue screen of death. Subsequent attempts to start it failed. The CPU/Video Chip are from Intel (i7) and they come as a single package with 2 dies soldered onto the motherboard.

The behavior: the power button lights up (green), but that is about all the laptop does. There is no display (built-in panel or external monitor).

What I have tested:

• removed the board and visually inspected in —> all checks out. There are no visible faults
• removed all non-essential components (wireless card, disk drive) —> still the same problem
• removed the memory module —> when I power on the laptop I can hear 4 (3+1) beeps. So the chip is not dead because it does run the POST (to a certain point i believe).
• removed the heat sink —> when i power on the laptop I can feel the CPU die getting hot. So the CPU at least gets power
• checked power to the disk drive —> no power
• checked power to the fan —> the fan does receive power (5v) but it does not spin (the PWM pin is not energized)

Checking the Lenovo forums there are some users complaining about similar issues, but, unlike myself, they all have discrete graphics chips (usually Nvidia). But i have the built-in Intel chip. Some say that heating up the video chip will bring things back to live, albeit temporarily.

Besides heating up the CPU/GPU combo, do you have other ideas? Some things I could check or a reliable source where I can download the schematics (i do not mind to pay for schematics, but the sites I found online looked a bit dubious…).

Thanks in advance for the help!

Bogdan

Dears

Thank you so much for the help so far!

The schematics were exactly what i needed.

What is the status now:

1. i have replaced the memory module and now the laptop starts (screen is on)
2. however, POST still fails due to FAN failure. The FAN failure message comes on the screen and the the laptop shuts down.

The memory module is indeed faulty because I plugged it into another system and that failed as well to boot.

The fan _seems_ to be faulty. It uses a 5-pin connector:

1. DC (in) —> 5v
2. FAN Start (in)—> 5V
3. GND
4. FAN ID (out) —> no idea what this is about
5. Tachometer (out)

I can confirm that during POST I have 5v on the DC in and FAN Start pin is pulled up (+5v). GND connection is ok too. However, the fan does not actually spin. The impeller is not stuck (it can easily rotate even if i blow on it with my mouth). I do not think i am capable of fixing the fan. The SMDs are absolutely tiny (majority of them are 0201) and (again) I was unable to find any schematics.

I am thinking of replacing it (approx $40) but then I cannot help thinking about how on earth it’s possible to have two components failing at the same time.

The laptop used to work just fine and it’s a personal device I had for years. One day I’ve started it, all was fine, but after some time all of a sudden it threw a BSOD and then never powered on. I can understand a failure of the memory module. I can understand a fan failure. But I find it very strange for 2 unconnected parts to fail at the same time.

It might be a bad coincidence, but I am also afraid of something else causing these failures.

Any advice/feedback is highly appreciated!

Cheers!

Bogdan

Dears

I was unable to repair the old fan. Since the motherboard looked like it was providing the correct voltage, I've decided to risk and buy a replacement fan. This turned out to be a good decision as, after replacing the fan, the laptop booted just fine. I've also put it though its paces and stressed it for a couple of hours and I;m happy to report that all is working fine. Hopefully I will get a few more years usage out of it.

Why exactly both the fan and memory module failed at the same time, I have no idea. Bad coincidence :)

⟐ Answered May 11, 2023 at 9:46 MST

⟐ Answer edited June 18, 2023 at 18:43 MST

⟐ Answered May 20, 2023 at 23:52 MST

⟐ Answered January 18, 2025 at 14:01 MST

⟐ Answered April 30, 2025 at 16:45 MST

⟐ Answered April 30, 2025 at 15:26 MST

⟐ Answer edited October 27, 2023 at 22:34 MST

I noticed when I removed the second battery it doesn't do this and work normal, how it is possible and if I replace the battery? Is gonna be fix? Have any one had same issue?

Yesterday I did unbox my new Lenovo ThinkPad T460s and the first thing that I did was that I booted in to BIOS and enabled Virtualizing and increased video memory to 512MB then I did boot from USB and did a clean install of Windows 10.

When I was in Windows 10 and installed Drivers I needed to reboot as usually.

But sometimes (every secound time) when I did reboot the computer did boot then after POST (after bios) it did reboot and then it booted just fine.

This issue did happen every secound time I did reboot the computer, but then I did update BIOS and also FW for the cipset and then the issue did disappear.

I did run MEMTEST all night and it did not show any errors either did Lenovos built in tests for the motherboard in BIOS.

I think it did disappear because of the BIOS update, but as my computer are so new I'm wondering if I should worry about it?

Should I replace it? I have 14 days remorse period that I can replace it in.