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Memory combination query
AMO
Posts: 1,464 Forumite
in Techie Stuff
Hi all,
My friend bought some memory from using the Crucial compatibility checker.
He got 2 x 1Gb.
Now he's gone 2 years later and run the checker to get another 2 x 1Gb.
The memory type is the same, but I believe the voltage is slightly different as is the CAS rating.
What would be the reason for why when starting up the BIOS identifies 4Gb but within Windows under System, only 2Gb appears?
Thanx
AMO
My friend bought some memory from using the Crucial compatibility checker.
He got 2 x 1Gb.
Now he's gone 2 years later and run the checker to get another 2 x 1Gb.
The memory type is the same, but I believe the voltage is slightly different as is the CAS rating.
What would be the reason for why when starting up the BIOS identifies 4Gb but within Windows under System, only 2Gb appears?
Thanx
AMO
0
Comments
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Are you sure the amount of memory shown in Windows <whatever> isn't closer to 3 GB? Where are you obtaining this figure from, by the way?
The maximum amount of memory addressable by 32 bits is 4 GB. Windows steals some of that address space, perhaps 0.75 GB, for tables and the like and sometimes the graphics card uses around 0.25 GB, so that the amount of real memory which Windows can actually use is around 3 GB (the actual amount can vary slightly between PCs), however much more than 3 GB has been installed.
If the amount you see is really only 2 GB, then I don't have a good answer...0 -
It would be useful to know which version of Windows you are referring to. For example if you look here:
http://msdn.microsoft.com/en-us/library/aa366778(VS.85).aspx
You'll see that there is a situation where a 32-bit version of Windows can only see 2Gb (i.e. if IMAGE_FILE_LARGE_ADDRESS_AWARE is not set).
It looks as though the problem may be within Windows, but if I were in this situation I would first use Memtest86 to check whether all of the 4Gb that the BIOS can see is functioning correctly. If not, you may need to manually tweak the CAS latency settings in the BIOS.0 -
You can only address 3.15Gb of ram. JG is wrong.
You have brought high density RAM and you need low density RAM. ALWAYS by RAM in matched pairs. Just buy 4GB RAM in two 2GB sticks.0 -
totalsolutions wrote: »You can only address 3.15Gb of ram. JG is wrong.
You have brought high density RAM and you need low density RAM. ALWAYS by RAM in matched pairs. Just buy 4GB RAM in two 2GB sticks.
Is high/low density RAM the same thing as single-sided/double-sided RAM?
Thanx
AMO0 -
Sorry, where am I wrong? Or are you saying that 3.15 GB is not "around 3 GB"?totalsolutions wrote: »You can only address 3.15Gb of ram. JG is wrong.
(I won't pull you up on the fact that 3.15 Gb means 3.15 gigabits...!)
Have a look at this Microsoft article, and I draw your attention specifically to the three paragraphs:
For example, if you have a video card that has 256 MB of onboard memory, that memory must be mapped within the first 4 GB of address space. If 4 GB of system memory is already installed, part of that address space must be reserved by the graphics memory mapping. Graphics memory mapping overwrites a part of the system memory. These conditions reduce the total amount of system memory that is available to the operating system.
The reduction in available system memory depends on the devices that are installed in the computer. However, to avoid potential driver compatibility issues, the 32-bit versions of Windows Vista limit the total available memory to 3.12 GB. See the "More information" section for information about potential driver compatibility issues.
If a computer has many installed devices, the available memory may be reduced to 3 GB or less. However, the maximum memory available in 32-bit versions of Windows Vista is typically 3.12 GB.0 -
totalsolutions wrote: »You have brought high density RAM and you need low density RAM.
You might be right, but I don't see how you can infer from their original post that they bought high density RAM.
In my experience, if you put high density RAM in a motherboard that can't take it, the BIOS generally won't report it as present, and usually won't boot if that is the only type of RAM present.
However, even if it does, Memtest86 will immediately show that the modules in question won't work with the motherboard.AMO wrote:Is high/low density RAM the same thing as single-sided/double-sided RAM?
No, it's not that simple. It depends on what type of RAM you have. For DDR SDRAM, take a look at the wiki:
http://en.wikipedia.org/wiki/DDR_SDRAM0 -
4 x 1 GB RAM?? It could be that the motherboard is capable of accepting different kinds of RAM, but not at the same time.0
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What type of ram ???
What model m/board ?????
Which version of windows ??0 -
Windows 32bit will only Address a total of 4GB of memory within the PC including all installed devices/ Graphics cards now can have upto 2GB of memory in themselves. Typically 512MB-1024Gb is common place.
I would check in the BIOS to see what the graphics memory is set too especially if you don't have a dedicated graphics card and it uses shared memory. The figure that this is set to will remove that amount of memory from being visible by the user through windows.
Secondly if 2 types of memory are installed motherboards will always run the memory at the slower settings that being the bus speeds and CAS timings.
I would say the issue is a combination of BIOS settings and previously installed hardware. Try resetting the BIOS to default settings and also install the memory sticks one by one, boot and see what is addressed in windows. You could also try the 2 new ones on their own to ensure windows recognises both without the old ones in situe.New PV club member. 3.99kW system. Solar Edge with 14 x 285W JA Solar panels. 55° West from south and 35° pitch.0
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