Aspire 5536G ZM-87 support

[Blasku]

Hi!
It's been a while since my last post here, and I've sold the AMD Turion Ultra ZM-87 since then to an acquaintance who has much better luck using the CPU except for one thing.
The problem is, that in his Acer Aspire 5536G laptop, the original processor was an Athlon QL-65, which only has a 333 MHz (667) memory controller and the new CPU runs all RAM at that maximum frequency also. He has tried all sorts of RAM modules, all of them PC2-6400. His laptop has the same motherboard chipset as my old TravelMate 5530G, so there's nothing in the hardware that should prevent the RAM from reaching a 800 MHz clock rate. And yet all the modules he's tried can only reach 667 MHz at best.
The last idea I have left is that the BIOS has some sort of restriction in it, or maybe it is the microcode that's not suitable and should be updated.
We've tried flashing Ahmed Hossam's modded BIOS for the AS5536G, but that didn't help, the built-in vBIOS is even less functional than in the stock BIOS (is it a correct assumption, that the vBIOS is built-in? I'm not absolutely sure).
I'll provide you the stock BIOS for the AS5536G, and the BIOS of a Fujitsu-Siemens Amilo Sa3650 as a donor HERE (same chipset, some models were even shipped with a ZM-86).
We'd be very grateful for any help you could provide with this strange problem!
The owner of the laptop will soon register on this forum, and then he'll be able to answer your questions.

[mivannem]

Hi, I'm the owner of the notebook. If you have any questions, I try to answer quickly.