Why does bios limit size of RAM recognized

[mcinvalek]

I have a great laptop; a Lenovo ideapad Y480. I've upgraded to an SSD and it runs very well. My issue is that bios only recognized 2x4 gigs Or 8 gigs total.

This is true with all computers, bios will recognize only so much. Why is that? Would it be possible to write a bios update so that the laptop would recognize 2x8gig or even 2x16 gig...not that I would go as high as 32.

Let me clarify. is it possible to write a bios update that will allow a computer's bios to recognize a great amount of RAM per slot; keeping the same voltage and type ddr3?

 

[lonewolf7]

This link shows you have a total of 8gigs of memory : http://shop.lenovo.com/us/en/laptops/ideapad/y-series/y480/#tab-tech_specs and the BIOS is showing that to you, did you added more memory lately ? If not then the bios is correct, add more memory(if supported) and the bios will show more.

 

[Tradesman1]

It will depend on the chipset, moat chipsets have a limitation as to the amount of DRAM it can run.....would of course also depend on your programming expertise to write a new BIOS

 

[Pinhedd]

I have a great laptop; a Lenovo ideapad Y480. I've upgraded to an SSD and it runs very well. My issue is that bios only recognized 2x4 gigs Or 8 gigs total.

This is true with all computers, bios will recognize only so much. Why is that? Would it be possible to write a bios update so that the laptop would recognize 2x8gig or even 2x16 gig...not that I would go as high as 32.

Let me clarify. is it possible to write a bios update that will allow a computer's bios to recognize a great amount of RAM per slot; keeping the same voltage and type ddr3?

Hi,

The important part of the firmware that you're referring to is known as the Memory Reference Code, or MRC. The MRC is the portion of the BIOS/UEFI ROM that initializes the memory subsystem. Intel and AMD both provide the MRC to firmware developers which then integrate it into their firmware which ships with the motherboard. The firmware developers can (and sometimes do) modify the MRC to extend the chipset's capabilities beyond that natively supported by Intel or AMD.

For example, neither Intel nor AMD support stacked-DRAM chips. These are DRAM chips that have multiple dies stacked on top of each other inside of the same package. Stacked memory is the only way to obtain certain high-density memory configurations, such as 128GiB in an unbuffered quad-channel configuration. Enabling this configuration requires the motherboard vendor's firmware engineers to modify the base MRC. However, doing so can cause problems, so many vendors avoid doing so, especially for mainstream and OEM platforms.

In theory, tweaking the MRC and packaging it into a firmware update will enable the platform to reach the physical extents of what the memory controller is capable of handling rather than the limitations that are imposed for stability, integrity, or marketing reasons.