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Mitac 7521+ with Ram recognising issue (soldered 256 MB)

Posted: Sat Jun 06, 2009 3:53 pm
by Lt.Cmdr.Ivan

I have a problem.

I replaced the Ram chips on the Mitac 7521+.

Originally it had only 128 MB of Ram soldered on the board. I replaced the original Memory modules (Hynix HY57V281620A) with larger ones (Infineon HYB 39S256160CT-7.5) from a new SDRam SOdimm Module that had the same pinout and voltage.

Now while the board runs perfectly (I already have tested the ram modules on board with the Memtest86+ programm and there were no errors) i have a small problem.

The board only detects half of the ram which means i am still stuck with 128 MB onboard ram.

Is there anyone out there who can give me advice on how to modify the bios (its a phoenix bios) to check for 256 instead of 128 MB onboard ram, or can tell me if there is a chip (the small inline configuration chip on the sodimm modules) i need to exchange to get the full ram working?

thank you very much for your help

Posted: Mon Jun 08, 2009 7:36 pm
by cp
did you check if the memory chip density compatible with the chipset of the mainboard? please post some details about the mainboard and its chipset.

Posted: Mon Jun 08, 2009 7:45 pm
by Lt.Cmdr.Ivan
The mainboard has a sis 630S chipset with Sockel 730 for Pentium 3 CPUs.

The complete specs are here: ... kation.doc

Edit - Fixed link for the OP. KW

Posted: Tue Jun 09, 2009 1:34 pm
by KachiWachi
Hynix HY57V281620A datasheet

4 Bank, 2M x 16, 128 Mbit Technology

Infineon HYB 39S256160CT-7.5 datasheet

4 Bank, 4M x 16, 256 MBit Technology

SiS 630S specifications

128 Mbit DRAM - 16x8
256 Mbit DRAM - 32x8


Posted: Tue Jun 09, 2009 5:15 pm
by Lt.Cmdr.Ivan
Ok, now i see the problem, i've chosen a ram module which isn't supported or expected to be 128 Mbit technology regarding the sis chipset.

So i better check and choose a proper ram module that is organized in the 32x8 arrangement.

Thank you very much for your help. :D

Posted: Wed Jun 10, 2009 12:19 pm
by KachiWachi