3 Gigs Ram or 4?

GeneO · 27 Oct 2010

DeaconFrost said:

The real question is what OS platform are you running. That will give the answer. If you have x86, don't bother upgrading. If you have or will switch to x64, go for it.

Or, save your money for a new board that supports more memory and that upgraded memory down the road.

rap33042 said:

I read some benchmarks regarding RAM upgrades not too long ago and it seems 3GB is a "sweet spot".
There wasn't that much improvement gained by adding the 4th Gig of RAM.

There is no sweet spot....unless you start talking about OS platform and intended uses for the computer. It isn't about benchmarks....it is about what you do with the computer. I have 8 GB and I am glad I do...as I can run multiple VMs at a time, without slowing down the host system. For an office-work only computer, 3 GB would be plenty. For a gaming system, I wouldn't go any lower than 4 GB.

Going to x64 does not guarantee that the OP will be able to see any more of that 4GB than the 32 bit OS would. In order to see all 4GB on x64, the computer's chipset must support at least 8GB of address space, and the chipset and system BIOS must support memory remapping. Without both of these the graphics memory will still use the upper 512MB+ of that 4GB of memory.

It is quite simple, the OS needs an address range to map the video memory and other device memory to so the system can read/write to the device using these addresses. This address range becomes unavailable for you to use as RAM. If your chipset only supports 4GB of RAM, it must map it the devices within that 4GB, so it is lost to you whether it is x64 or not. If your chipset supports 8GB or more, then the BIOS and chipset can map the devices to the upper part of the 8GB of address space *if* your BIOS has the memory remapping option which permits this to happen. In this case, if you have 4GB of RAM the full 4GB is available in X64 because the devices are mapped to addresses that are higher than that of the physical RAM.

- Gene

DeaconFrost · 27 Oct 2010

GeneO said:

Going to x64 does not guarantee that the OP will be able to see any more of that $GB than the 32 bit OS would. In order to see all 4GB on x64, the computer's chipset must support at least 8GB of address space, and the system BIOS must support memory remapping. Without both of these the graphics memory will still use the upper 512MB+ of that 4GB of memory.

I've never heard of the support for 8 GB being a requirement. That seems awfully farfetched, and I know I've set up OEM systems that max out at 4 GB, yet can use all 4 GB with an x64 OS. Besides, with any decent quality chipset, the memory remapping options should be already available. I will only use Intel chipsets, and they have had full support going back to the early 9xx chipsets.

Link us to a description of the 8 GB support being a requirement...I've never heard of that.

stormy13 · 27 Oct 2010

Already posted a link about it,

The system memory that is reported in the System Information dialog box in Windows Vista is less than you expect if 4 GB of RAM is installed

maybe this bit will help,

For Windows Vista to use all 4 GB of memory on a computer that has 4 GB of memory installed, the computer must meet the following requirements:

The chipset must support at least 8 GB of address space. Chipsets that have this capability include the following:
- Intel 975X
- Intel P965
- Intel 955X on Socket 775
- Chipsets that support AMD processors that use socket F, socket 940, socket 939, or socket AM2. These chipsets include any AMD socket and CPU combination in which the memory controller resides in the CPU.
The CPU must support the x64 instruction set. The AMD64 CPU and the Intel EM64T CPU support this instruction set.
The BIOS must support the memory remapping feature. The memory remapping feature allows for the segment of system memory that was previously overwritten by the Peripheral Component Interconnect (PCI) configuration space to be remapped above the 4 GB address line. This feature must be enabled in the BIOS configuration utility on the computer. View your computer product documentation for instructions that explain how to enable this feature. Many consumer-oriented computers may not support the memory remapping feature. No standard terminology is used in documentation or in BIOS configuration utilities for this feature. Therefore, you may have to read the descriptions of the various BIOS configuration settings that are available to determine whether any of the settings enable the memory remapping feature.
An x64 (64-bit) version of Windows Vista must be used.

DeaconFrost · 27 Oct 2010

I swear I've had Dell OEM systems with 945 chipsets running with 4 GB of usable memory.

stormy13 · 27 Oct 2010

Might not want to swear too loudly as according to Intel it is only up to 4 GB on that chipset,

Intel® 945G Express Chipset - Overview

Up to 10.7 GB/s of bandwidth and 4GB memory addressability for faster system responsiveness and support for 64-bit computing.

Too lazy to go looking for them but we have had quite a few threads here from some with 8 GB and only have around 7 GB or so available from running into this same thing because the chipset only supports up to 8 GB. Once you install the max ram the chipset can support it doesn't matter whether the OS is 32 or 64 bit if the memory re-mapping option isn't supported, as all devices still have to be addressed somewhere and if it can't use virtual addressing above 4 GB it takes it from the 4 GB.

LiquidSnak · 27 Oct 2010

If you are purchasing RAM, go for the 4GB setup. That way you won't have to buy any later. If you are running 32, then your onboard GPU will have some nice RAM to work with that won't detract from the RAM available for windows.

GeneO · 27 Oct 2010

DeaconFrost said:

GeneO said:

Going to x64 does not guarantee that the OP will be able to see any more of that $GB than the 32 bit OS would. In order to see all 4GB on x64, the computer's chipset must support at least 8GB of address space, and the system BIOS must support memory remapping. Without both of these the graphics memory will still use the upper 512MB+ of that 4GB of memory.

I've never heard of the support for 8 GB being a requirement. That seems awfully farfetched, and I know I've set up OEM systems that max out at 4 GB, yet can use all 4 GB with an x64 OS. Besides, with any decent quality chipset, the memory remapping options should be already available. I will only use Intel chipsets, and they have had full support going back to the early 9xx chipsets.

Link us to a description of the 8 GB support being a requirement...I've never heard of that.

Well the link has been posted. The reason is you need address space to map those devices to beyond the 4GB of the RAM you want to use. 8GB is the next jump up in address space supported by the chipsets.

So with the 945 chipset, you don't get much benefit beyond 3GB of RAM.

As for the post that says get 4GB you will use it later - I hardly think so. You don;t gain anything by going to 64 bit, and if you get a new computer, the memory won't be compatible so it is a waste.

- Gene

GeneO · 27 Oct 2010

DeaconFrost said:

I swear I've had Dell OEM systems with 945 chipsets running with 4 GB of usable memory.

I have one of those. I get 3.25 usable with Windows 7 64 bit.

Maybe you didn't have an awful lot of video RAM?

Solarstarshines · 27 Oct 2010

wow another EPIC post

DeaconFrost · 28 Oct 2010

GeneO said:

Maybe you didn't have an awful lot of video RAM?

256 MB Nvidia 7600GT and later a 7900GS. That's good to know for the future, but by now, the 945 chipset is, to be polite, aged....so it shouldn't be much of an issue going forward.