[HELP] Asus A42JK CPU upgrade

BIOS/UEFI Modding BIOS Modding Guides and Problems
1

Hello,

I attempted upgrading the processor in my A42JK from i5-520M to i7-840QM. The official (and latest) BIOS for this laptop doesn’t support the i7 processor I want to install in. So, I upgraded the microcode for this CPUID (0x106E5) from the rev3 (which predates the i7 launch) to the latest available rev7 and flashed it over the official one. Still, I have met no success as the laptop turns on but screen doesn’t display anything, neither is the backlight on. Soon after, the fan starts going full speed and I can feel warm air exhausting and the heatsink area getting warm.

I’m wondering if it is an issue of the BIOS not getting past the check for iGPU (which the existing i5 has; i7 doesn’t) and hence not able to POST and/or display anything. Therefore, I am requesting help on whether I can bypass this check, if that’s the issue. Or even simply that the socket/chipset does not support a higher TDP processor. Not sure of any other possible issues, but do please share with me too if you are aware.

I’ve attached the official and the modded BIOS which I did microcode update for CPUID 106E5 (plat. 13). I hope it helps and I do hope I can get some help on this. I really want to get it working and this is the second step towards it. I’m not giving up until I exhaust all possible means. Thanks.

Vital info
Processor: Intel Core i5-520M (35W TDP) [Upgrading to i7-840QM: 45W TDP, no iGPU; CPUID 0x106E5; SLBMP]
GPU: ATi Mobility Radeon HD 5145 (no switchable graphics)
Chipset: Intel HM55 (Socket G1)
Official BIOS vers: 218

Tools
MMTool 4.50.0.23
Intel microcode (dated 4th Nov 2016)
Intel microcode extract tool

A42JK BIOS.zip (1.9 MB)

2

You can try a clear CMOS by removing its battery but it won’t help as this is almost certainly happening due to the missing iGPU. I assume that the motherboard has been designed with one in mind and thus the screen is connected to the integrated Intel GPU so no post. It’s simple to verify that and exclude all possible issues due to modding. Just place the working i5 back and check if it works with the modded BIOS. If it does, the problem is with the iGPU and not your mod.

3

Yes I have tried them and that’s why I’ve come to this conclusion. Hence, I’m wondering if it’s possible to mod the BIOS to bypass the iGPU check/requirement etc.

4

If the i5 works then it’s the iGPU. It’s not something you can remove or bypass (even if someone knew how) as the screen is probably/usually connected physically to the iGPU.

5

Not sure if it’d help but I found schematic diagrams for a couple of, what I think are, related products of Asus.

A/K42Jr (same chipset and CPU offerings, but with HD5470 instead of HD5145): HERE
K72JK (same specs as my A42JK, but with 17.3" screen): HERE

Hopefully someone here on the forums can inform me on whether the LVDS actually goes through the iGPU of the Core i3/i5 of this series. Since if that’s how it works, the i7 would definitely not work as it doesn’t have an integrated GPU.

Thanks.