BSOD upon swapping HD between two same model X61

[E350]

Hey guys and girls:

I have been ignoring a loud fan and working away on my X61 for almost a year now. Last week I got my first couple failures to boot because of "Fan Error" at start up. (It now starts intermittently, but the writing is on the wall I need to replace the fan.)

I have an identical model X61 back up, so I put the Hard Drive from the X61 with the fan issues along with its 8Gb Crucial Memory into the back up X61 and consistently half-way through boot I get the Blue Screen Of Death. (Questioning recent hardware changes.)

So, since the machines are both the same model, I assume that either:

1. The WIFI cards are not the same (I need to take the palm rests off and look);
2. I installed Middleton's BIOS on the one but not on the back up;
3. There is something in BIOS or in W7 Home Premium 64-bit which recognizes and requires the same Machine Code for the motherboard for it to boot properly?
4. Any other suggestions?

Finally, how can I tell if I installed Middleton's BIOS on the back up X61?
Can I reinstall it without problems if I cannot tell?
And finally, where can I find the current Middleton's BIOS for the X61?

Thanks in advance for your help.

[hhhd1]

check the bios settings, might be the ahci settings,
or the middleton bios affecting the sata interface

[DaKKS]

It should work, but this has happened to me too. Same identical machines, bios settings and it still doesnt work. Happens more often with dells than lenovos in my experience

[E350]

Good ideas. I will start each machine and compare their BIOS settings side by side.
Also, any sugggestion where I can find the current Middleton BIOS?
(To make sure that I have it installed on the backup X61.)

[RealBlackStuff]

M's BIOS http://ali.dj/blog/sata-ii-support-for- ... 61-x61-r61

[E350]

RBS: Thanks again buddy! Have a lovely day!