Motherboard & RAM compatibility

[Pavlos313x]

Hello,

I have an old system, which I think it has ram problems so I am going to replace the ram.

My question is this:
My motherboard GA-X48T-DQ6 supports up to 8GB DDR3 as per Gigabyte specs.

But I've been reading that since X48 chipset supports 16GB RAM the motherboard can take it too, since the only reason that Gigabyte stated 8GB as max RAM, was because at that time 4GB modules didn't exist.

Is this true? Can I put 16GB RAM instead of just 8GB?

Thank you in advance.

 

[neeyik]

Not sure where you read 16 GB from, but Intel themselves specify that X48 as only supporting a maximum of 8 GB:

Product Specifications

quick reference guide including specifications, features, pricing, compatibility, design documentation, ordering codes, spec codes and more.

ark.intel.com

 

[Pavlos313x]

Ah, sorry. I was reading various posts and didn't think to check intel's specs to be sure. Thank you.

 

[HardReset]

Not sure where you read 16 GB from, but Intel themselves specify that X48 as only supporting a maximum of 8 GB:

Product Specifications

quick reference guide including specifications, features, pricing, compatibility, design documentation, ordering codes, spec codes and more.

ark.intel.com

Since when manufacturer websites are reliable source for things like this? General formula for max memory on DDR, DDR2 and DDR3 era goes like this:

Max amount of memory slots supported * max sized memory module available when product is released = max memory. Very good example of this are AMD870/970 chipset motherboards with 4 slots. Some "supported" 32GB while some only "supported" 16GB. Only difference was that some manufacturers updated product pages (after 8GB DDR3 modules came available) and some did not. There are many other examples but that came first in mind.

Max amount of memory slots rarely if ever changes but max sized memory module could get bigger. Question: is there hard limit for memory size on x48 chipset? There is at least one, max memory address size is 36 bit that means max memory x48 could theoretically support 64GB. That's four times more than 16GB. Anything else? I really doubt it.

I see no reasons why 16GB (or even 32GB) couldn't work on x48 chipset. Main problem is that motherboards are not tested (why bother to test with any more Intel supports?) with more than 8GB memory. Everything above 8GB is at your own "risk" (if there is any risk for that old stuff anyway). I'm quite sure it's very possible to make x48 motherboard that supports 32GB RAM, another question is who bothers to make one.

Answer for your question is: perhaps. If it doesn't work, you cannot blame anyone but yourself.

 

[Pavlos313x]

Answer for your question is: perhaps. If it doesn't work, you cannot blame anyone but yourself.

Yea, if I had memory to test, I would of But I don't and wanted to know if it was possible in order to buy new ram at 2x 8gb instead of 2x 4gb.

Since I don't have money to waste just for a test, I am going to get 8gb again and wait until I buy my new system to upgrade.

If I decide to keep my old Beast after I buy my new one, I may try to put 16GB on it to see what happens.

 

[neeyik]

Well, to continue using the manufacturer's website, here's everything that Intel has to say on the matter:

System Address Map
The MCH supports 64 GB (36 bit) of host address space and 64 KB+3 of addressable I/O space. There is a programmable memory address space under the 1 MB region which is divided into regions which can be individually controlled with programmable attributes such as Disable, Read/Write, Write Only, or Read Only. Attribute programming is described in the Register Description section. This section focuses on how the memory space is partitioned and what the separate memory regions are used for. I/O address space has simpler mapping and is explained near the end of this section.

The MCH supports PCI Express upper pre-fetchable base/limit registers. This allows the PCI Express unit to claim I/O accesses above 36 bit, complying with the PCI Express Specification. Addressing of greater than 8 GB is allowed on either the DMI Interface or PCI Express interface. The MCH supports a maximum of 8 GB of DRAM. No DRAM memory will be accessible above 8 GB.

Main Memory Address Range (1MB - TOLUD)
This address range extends from 1 MB to the top of Low Usable physical memory that is permitted to be accessible by the MCH (as programmed in the TOLUD register). All accesses to addresses within this range will be forwarded by the MCH to the DRAM unless it falls into the optional TSEG, or optional ISA Hole.

Main Memory Address Space (4 GB to TOUUD)
The MCH supports 36 bit addressing. The maximum main memory size supported is 8 GB total DRAM memory. A hole between TOLUD and 4 G occurs when main memory size approaches 4 GB or larger. As a result, TOM, and TOUUD registers and RECLAIMBASE/RECLAIMLIMIT registers become relevant.

The new reclaim configuration registers exist to reclaim lost main memory space. The greater than 32 bit reclaim handling will be handled similar to other MCHs.

Upstream read and write accesses above 36-bit addressing will be treated as invalid cycles by PCI Express and DMI.

Top of Memory
The “Top of Memory” (TOM) register reflects the total amount of populated physical memory. This is NOT necessarily the highest main memory address (holes may exist in main memory address map due to addresses allocated for memory mapped I/O above TOM). TOM is used to allocate the Intel Management Engine's stolen memory. The Intel ME stolen size register reflects the total amount of physical memory stolen by the Intel ME. The ME stolen memory is located at the top of physical memory. The ME stolen memory base is calculated by subtracting the amount of memory stolen by the Intel ME from TOM.

The Top of Upper Usable Dram (TOUUD) register reflects the total amount of addressable DRAM. If reclaim is disabled, TOUUD will reflect TOM minus Intel ME stolen size. If reclaim is enabled, then it will reflect the reclaim limit. Also, the reclaim base will be the same as TOM minus ME stolen memory size to the nearest 64 MB alignment.

TOLUD register is restricted to 4 GB memory (A[31:20]), but the MCH can support up to 16 GB, limited by DRAM pins. For physical memory greater than 4 GB, the TOUUD register helps identify the address range in between the 4 GB boundary and the top of physical memory. This identifies memory that can be directly accessed (including reclaim address calculation) which is useful for memory access indication, early path indication, and trusted read indication. When reclaim is enabled, TOLUD must be 64 MB aligned, but when reclaim is disabled, TOLUD can be 1 MB aligned.

Now that register is rewritable, by the BIOS, so HardReset is correct in saying that theoretically it can support more than 8 GB (although no more than 16 GB). However, it's obviously down to the motherboard vendor to offer that option.