Is T420 BIOS downgrade possible?

Hi guys, my laptop had a problem 2 weeks ago with constant freezing and lag, I sent in to repair and they replaced the motherboard under warranty. When I got the unit back, the BIOS is at an older version which the system update tool recommended me to upgrade and after it finished and rebooted the exact same problem is back. Currently the problematic version is 83ET70WW 1.40. I think the old one was 1.15 or something like that.

When theres no problem, my memory runs at 1600MHz and after the bios update supposedly both times, the RAM under clock itself to 1333MHz and the freeze+lag comes back.

I have never done a downgrade before so coming up here to look for some pro advice. thanks for helping!

Also which version would be a good one to downgrade to? since 1.15 seems too obsolete now.

EDIT: my memory is 8gb Kingston HyperX 1600 PnP (2x4G)

 

Downgrade is possible, just flash it with an older BIOS. The ones after 1.26 or something fix the fan pulsing, so I'd go for one of those.

 

I couldnt find the fan pulsing fix from their update log, so is 1.26 the good one?

Code:

Summary of Changes

  Where: <   >        Package version
         UEFI:        UEFI BIOS version
         ECP:         Embedded Controller Program version
         [Important]  Important update
         (New)        New function or enhancement
         (Fix)        Correction to existing function

<1.40>
 UEFI: 1.40 / ECP: 1.19
- (Fix) Fixed an issue where specific hard disks might not be detected after
        resuming normal operation from standby/sleep state.
- (Fix) Fixed an issue where an unnecessary fan error message might be shown.

<1.39>
 UEFI: 1.39 / ECP: 1.18
- (Fix) Fixed an issue where incorrect battery capacity might be shown in some
        battery benchmark programs.
- (Fix) Fixed an issue where the computer failed to resume normal operation from
        hibernation state after running Setup Defaults by the F9 key in the
        ThinkPad Setup menu.
- (Fix) Fixed an issue where the Power-On NumLock function in ThinkPad Setup did
        not work.

<1.37>
 UEFI: 1.37 / ECP: 1.11
- (Fix) Fixed an issue where the Intel Pentium CPU models might fail to resume
        normal operation from standby/sleep state.
- (Fix) Fixed an issue where the maximum number of password attempts through WMI
        was not 3.

<1.36>
 UEFI: 1.36 / ECP: 1.11
- (Fix) Fixed an issue that might return a time-out error in SATA compatibility
        mode.
- (Fix) Fixed an issue where the UEFI BIOS might not be updated correctly when
        running the BIOS update after resuming normal operation from standby/
        sleep state.

<1.35>
 UEFI: 1.35 / ECP: 1.11
- (New) Improved memory resource allocation process to reserve more memory space
        for optional hardware devices.
- (Fix) Fixed an issue where some keys of the external USB keyboard might not
        work correctly on PBE of McAfee Endpoint Encryption software.
- (Fix) Fixed an issue where intranet account login might fail with ThinkVantage
        Hardware Password Manager.

<1.34>
 UEFI: 1.34 / ECP: 1.11
- (Fix) Fixed an issue where the computer might fail to boot when connected some
        Smartphones with the USB port. The following smartphones were tested:
          Motorola: Droid 2, Droid X
          HTC: Nexus One, EVO, Droid Incredible, Droid Incredible 2, ThunderBolt,
               Aria
          Samsung: Captivate, Galaxy Tab

<1.34>
 UEFI: 1.34 / ECP: 1.11
- (New) Improved system performance when a heavy software was executed with the
         65W AC adapter.
- (New) Added support for some USB keyboards with a fingerprint reader.
- (New) Added support for the option to change product name and version format
        in SMBIOS.
- (Fix) Fixed an issue that might cause slow system boot.
- (Fix) Fixed an issue where the computer might fail to boot when connected some
        Smartphones with the USB port.
- (Fix) Fixed an issue where the BIOS Update Utility failed to update the BIOS
        when DEP (Data Execute Prevention) was enabled.

<1.33-1.10>
 UEFI: 1.33 / ECP: 1.10
- (New) Disabled keyboarding while the lid was closed to avoid unexpected key
        input when the computer was held with the lid closed.

<1.33>
 UEFI: 1.33 / ECP: 1.09
- (Fix) Fixed an issue where the computer might not be booted from bootloader
        program.

<1.32>
 UEFI: 1.32 / ECP: 1.09
- (New) Enhanced the warning function of the ThinkPad Battery 27++ (9 Cell Slice
        Battery).
- (Fix) Fixed an issue where a 1820 error might occur at power-on when the
        external fingerprint reader device was attached to the computer while
        the integrated fingerprint reader was disabled in the ThinkPad Setup.
- (Fix) Fixed an issue where the computer might fail to boot when connected the
        Smartphone with the USB port.
- (Fix) Fixed an issue where the ThinkPad Battery 27++ (9 Cell Slice Battery)
        might not supply power even when the internal main battery became empty.

<1.31>
 UEFI: 1.31 / ECP: 1.08
- (Fix) Fixed an issue for volume licensed Windows support.

<1.30>
 UEFI: 1.30 / ECP: 1.08
- (New) Added support for the Password Beep function.
- (New) Increased the number of configurable boot devices by BootOrder option of
        Windows WMI script.
- (Fix) Fixed an issue where the BitLocker function could not be enabled on
        Windows 64-bit.
- (Fix) Fixed an issue where PXE boot might fail.
- (Fix) Fixed an issue where the fingerprint authentication associated with some
        password strings might fail.

<1.29>
 UEFI: 1.29 / ECP: 1.08
- (New) Added support for the Resetting of the Cryptographic Key for Full Disk
        Encryption (FDE) Hard Drives (HD) and Erasing of the Solid State Drive
        (SSD).

<1.28>
 UEFI: 1.28 / ECP: 1.08
- (Fix) Fixed an issue where the Intel TXT feature might not be enabled when the
        Security Chip was activated and the Intel TXT feature was enabled at the
        same time by ThinkPad BIOS Settings Windows program.
- (Fix) Fixed an issue where the Bluetooth wireless status indicator might be
        changed after running Windows WMI script.

<1.27>
 UEFI: 1.27 / ECP: 1.08
- (New) Added support for a new type of the Embedded Controller.
- (Fix) Fixed an issue where the expected machine serial number might not be
        stored in the serial number field of SMBIOS type 3 structure.
- (Fix) Fixed an issue where the VRAM size was allocated to fixed 128MB, not up
        to 1GB with the Intel graphics mode on Windows XP.
- (Fix) Fixed an issue where some system settings could not be changed by
        Windows WMI script.

<1.26>
 UEFI: 1.26 / ECP: 1.08
- (New) Updated Computrace ROM to version 80.895.
- (Fix) Fixed an issue where some security settings in ThinkPad Setup could not
        be changed by Windows WMI script.
- (Fix) Fixed an issue where the computer might not be booted from the hard disk
        with Linux installed if there was no active partition there.
- (Fix) Fixed an issue where the computer with large-capacity memory installed
        might fail to resume normal operation from standby/sleep state.
- (Fix) Fixed an issue where a particular AC adapter might not be detected.

<1.23>
 UEFI: 1.23 / ECP: 1.07
- (New) Added support for Microsoft Windows Vista 32-bit, 64-bit.
- (New) Added support for the Intel Pentium CPU models.

<1.22>
 UEFI: 1.22 / ECP: 1.07
- (Fix) Fixed an issue where specific CPU models might fail to resume normal
        operation from standby/sleep state.

<1.21>
 UEFI: 1.21 / ECP: 1.07
- (New) Added support for the mSATA preload model.
- (New) Added support for the function to configure Boot Priority Order via WMI
        interface.
- (Fix) Fixed an issue where OS boot might fail from the CD.

<1.16>
 UEFI: 1.16 / ECP: 1.07
- (New) Added support for the Intel i3-2310M CPU model.

<1.15>
 UEFI: 1.15 / ECP: 1.06
- (New) Added support for ThinkPad T420,T420i NVIDIA NVS 4200M installed models.

<1.14>
 UEFI: 1.14 / ECP: 1.05
- (New) Initial release for ThinkPad T420,T420i. 

 

I'm not sure about the T420, but on the W520 it was 1.26. I don't think it was really stated as a fix, though.

 

1.36 supports DDR3 1600 and 1.39 starts limiting ram speed to 1333 but personally I don't see a problem with that, its only noticeable in benchmark scores.

 

That's the answer I'm looking for. But If the limit was intentional then I have no idea why the comp would get random freezes and really bad performance when limited.

 

Update: Flashed to 1.37 ram running at 1600 and gonna do some test see if its stable