How to test T420 motherboard without screen or HDD?

[85101]

I have a T420 with a broken screen and no hard drive. The CPU and RAM are there. Is there a way to determine if the motherboard can boot to BIOS? I have access to a dock and external monitors.

[RealBlackStuff]

You need to put in:
-keyboard
-DC-connector, connect AC-adapter to it
-CPU + fan
-some RAM
-CMOS-battery (should also work without)
Connect an external monitor to the VGA port, then boot and press F1 to go into BIOS.
You may also need to press Fn/F7 a few times if no monitor output.

[rkawakami]

Using an external monitor, either through the laptop's own VGA port or via a docking station, you should be able to see if the system is booting. However, I would recommend the following procedure:

- Remove all memory, peripheral boards (PCIe, ExpressCard, modem, etc.) and disconnect the LCD cables from the motherboard and attempt to boot (you don't need an external monitor for this). You should get a 1-3-3-1 beep code. This indicates that the motherboard has at least identified that there's no memory installed. If there's no beeps, it can mean you have a non-booting motherboard OR that there's something wrong with the audio system (speakers are missing/muted/broken, or the headphone jack is broken). Assuming you do get the 1-3-3-1 beep code....
- Shut down the system and put one memory module back in. You should attach a monitor for this step. Power back up. If there's no beep code, the motherboard has recognized the memory module. However, there's a small chance that a defective module would allow the system to power up without any beeps. If there's no display on the external monitor, press the Fn+F7 key combination. That command cycles the active display between the LCD and external monitor. If there's still no activity, shut the system down and try another memory module. If possible, verify the memory module(s) work in another similar system.
- Assuming you can boot successfully into BIOS, shut the system down and re-attach one of the peripheral boards then attempt to boot again. If the system fails to boot, the last board you re-installed is probably damaged. Continue to re-attach one board at a time.

[85101]

Using Fn+F7 to change the display output worked after reseating the RAM modules. Thanks for the help.

[Temetka]

Those suggestions are fine and dandy.

But are they fun?

No.

You want to see if the mobo works?

Power on the system. Dump 1/2 gallon of water on it.

If there are sparks, the mobo was good.

And now you have your answer.