Lexar Computer Memory Upgrades Support

Why doesn't my Windows® PC recognize the whole 4GB of memory I installed?

Not only is there a maximum amount of memory that your computer motherboard can accept, there is also a maximum amount of memory that your operating system (OS) can accept. For instance, when you install 4GB of memory in a 32-bit Windows system (the most common version; 64-bit systems are typically used by high-end users), your system reports only 3GB or 3.5GB.

First , we can assure you, there isn't a problem with the memory. While Windows allows for 4GB of memory to be addressed, it does not equate to 4GB of physical memory.

Some of the memory (regardless of how much you have installed) is reserved for use by the devices that you are using, such as a graphics card, PCI card, integrated network connections, etc, meaning it is unavailable for use as normal main memory.

Upon startup, your system calculates the amount of memory needed for these devices; if you haven't maxxed out the memory in your system, it's invisible to you, and all your physical memory (the installed RAM) is available for use. However if you've maxxed out the DRAM in your system, this amount will be deducted from your physical memory, so you can't use 100% of your DRAM.

The maximum memory limitation varies by operating system, For instance, the 4GB memory limitation doesn't exist in 64-bit versions of Windows.

Note for Windows Vista users:
Microsoft has addressed this issue for Windows Vista with its Service Pack 1.

If you have a system board that can handle more than 4GB of memory and a processor capable of handling x64 instructions and memory remapping, Vista SP1 can help. Because of Windows and the driver stacks, Windows loaded them into 'high' memory locations to avoid potential driver compatibility issues. (Meanwhile, the 32-bit versions of Windows Vista limit the total available memory to 3.12 GB.) VistaSP1 has other features to enhance your computing, so we recommend you add it, if you haven't done so already.

If you are running Windows XP, you can cosmetically correct the issue by editing the Physical Address Extension settings.

Memory maximums for current Microsoft® Windows OSs include:

Windows Vista (32 bit) 
Ultimate: 4 GB
Enterprise: 4 GB
Business: 4 GB
Home Premium: 4 GB
Home Basic: 4 GB
Starter: 1 GB

Windows XP (32 bit) 
Professional: 4 GB
Home: 4 GB
Starter Edition: 512 MB

Windows Server 2003 (32 bit) 
Datacenter SP2: 128 GB
Enterprise SP2: 64 GB
Standard SP1: 4 GB*
Datacenter R2: 128 GB
Enterprise R2: 64 GB
Standard R2: 4 GB*
Web Edition: 4 GB*
Small Business Edition: 4 GB*

* Certain Microsoft server operating systems can support over 4GB of memory via Physical Address Extension (PAE). Please refer to Microsoft knowledgebase article located here for more information.

Windows Server 2008 (32 bit) 
Datacenter: 64 GB
Enterprise: 64 GB
Standard: 4 GB
Web Server: 4 GB

Windows Vista (64 bit) 
Ultimate: 128 GB
Enterprise: 128 GB
Business: 128 GB
Home Premium: 16 GB
Home Basic: 8 GB

Windows XP (64 bit) 
Professional: 128 GB 
Windows Server 2003 (64 bit)
Datacenter SP2: 2 TB
Enterprise SP2: 2 TB
Standard SP1: 32 GB
Datacenter R2: 1 TB
Enterprise R2: 1 TB
Standard R2: 32 GB
Small Business Edition: 128 GB

Windows Server 2008 (64 bit) 
Datacenter: 2 TB
Enterprise: 2 TB
Standard: 32 GB
Web Server: 32 GB

Top
After adding memory I get an error message and my PC won't boot. Why?

This error message is consistent with a couple of problems. The most common is that when reaching to install your memory, you accidentally bumped a cable (perhaps a hard drive cable). The first thing we suggest is to reseat all the cables in your computer, this includes the cable to the hard drive and hard drive power. When you turn on the computer, do you hear the hard drive start to spin or see the hard drive light flicker?

The second and much simpler solution may be that you have a floppy disk (that is not a boot disk) in your floppy drive. Please check to see that there are no disks in your floppy drives. If this doesn't help, please contact us at support@lexar.com or call (510) 413-1275. We will be happy to continue troubleshooting for you!

Top
What is the maximum amount of RAM the Windows operating system can handle?

That depends on two factors: the amount of memory your computer hardware can handle, and the amount of memory your Microsoft® Windows® operating system (OS) can handle.

First, your computer hardware (motherboard) is designed to hold a maximum amount of RAM. 

Second, the OS maximum is the maximum amount of memory that your particular version of Windows, Linux, or Mac® OS can handle. 

When purchasing your memory upgrade, make sure that you do not exceed the lower of the two maximums (OS and computer maximums.) Too much RAM can lower your system's performance or cause other problems. (In most cases, the system maximum is lower than the OS maximum.)

Windows Vista (32 bit)
Ultimate: 4 GB
Enterprise: 4 GB
Business: 4 GB
Home Premium: 4 GB
Home Basic: 4 GB
Starter: 1 GB

Windows XP (32 bit)
Professional: 4 GB
Home: 4 GB
Starter Edition: 512 MB

Windows Server 2003 (32 bit)
Datacenter SP2: 128 GB
Enterprise SP2: 64 GB
Standard SP1: 4 GB*
Datacenter R2: 128 GB
Enterprise R2: 64 GB
Standard R2: 4 GB*v 
Web Edition: 4 GB*
Small Business Edition: 4 GB* 

* Certain Microsoft server operating systems can support over 4GB of memory via Physical Address Extension (PAE). Please refer to Microsoft knowledgebase article located here for more information.

Windows Server 2008 (32 bit)
Datacenter: 64 GB
Enterprise: 64 GB
Standard: 4 GB
Web Server: 4 GB

Windows Vista (64 bit)
Ultimate: 128 GB
Enterprise: 128 GB
Business: 128 GB
Home Premium: 16 GB
Home Basic: 8 GB

Windows XP (64 bit)
Professional: 128 GB

Windows Server 2003 (64 bit)
Datacenter SP2: 2 TB
Enterprise SP2: 2 TB
Standard SP1: 32 GB
Datacenter R2: 1 TB
Enterprise R2: 1 TB
Standard R2: 32 GB
Small Business Edition: 128 GB

Windows Server 2008 (64 bit)
Datacenter: 2 TB
Enterprise: 2 TB
Standard: 32 GB
Web Server: 32 GB

Here are the OS maximums for some older versions of Microsoft Windows:

Windows 95: 1GB
Windows 98: 1GB
Windows 98SE: 1GB
Windows ME: 1.5GB
Windows NT: 4GB
Windows 2000 Professional: 4GB
Windows 2000 Server: 4GB
Windows 2000 Advanced Server: 8GB with PAE enabled
Windows 2000 Datacenter Server: 32GB with PAE enabled

Here are the maximums for some other platforms:

OS X (including v. 10.4 "Tiger"): 8GB due to current hardware limitations (the current maximum memory capacity of Apple's highest-end system, the Power Mac G5)

OS 9.x: 1.5GB (no single application can utilize more than 1GB)

Red Hat Linux 2.4 kernel: 64GB

Top
How much memory is in my system?

There are several ways to tell how much RAM is currently installed in your computer.

If you have Windows, you can right-click on the "My Computer" icon and select "Properties." The dialog box will tell you how much RAM you have.

Top
How can I tell if I installed my memory correctly?

First, make sure that your module sits in the socket securely. If there are clips on the socket, they should snap into place to hold the module.

Next, turn on your computer. If it powers up and runs properly with no error messages, chances are that you installed the memory correctly. It's that easy!

For more information about installing memory, see our installation guide.

Top
How long does RAM last?

Top-quality RAM usually continues to operate properly for decades. Because it has no moving parts, RAM really doesn't wear out, and your RAM will probably continue to work just fine long after you've gotten rid of your current computer.

If RAM is going to fail, it usually fails near the beginning of its life. To eliminate as many potential failures as possible, we put our RAM through extensive "burn-in" and testing before it leaves the manufacturing facility. That's why we can offer a lifetime limited warranty on all Lexar modules.

Top
More memory means longer laptop battery life.

Picture this: You're finishing a huge project. Just as you start to click Save on your laptop, the screen goes black. Out of power-again.

We've all been there, but there is a way to get longer life from the battery in your laptop. Adding RAM can make your battery last as much as 30% longer!

Laptop battery performance graph 
How it works
When you're working on your laptop, it looks for information in your RAM. If your computer doesn't find what it is looking for in RAM, it has to access your hard drive. Unfortunately, your hard drive is not only slower than RAM, it uses approximately 30 times more power than 64MB SDRAM.

The more RAM you have, the less often you'll need to access your hard drive. The less often you access your hard drive, the longer your battery will last.

Laptop Components Typical Power*

Screen**

6 Watts

Hard Drive Active

4 Watts

Hard Drive Idle

0.1 Watts

SDRAM (32MB)

.12 Watts

SDRAM (64MB)

.13 Watts

* All values are approximate

** For a laptop, the screen represents one of the largest constant power drains on the battery.

Test Results
To test the impact of RAM on laptop battery life, engineers at Micron, Lexar's parent company, simulated standard computer operation on a variety of laptop models. Each model was tested with various levels of SDRAM.

Upgrading from 32MB to 64MB of SDRAM gave an average improvement of approximately 30%. Moving beyond 64 MB gave slight improvements on Windows 98 machines running standard business software. However, if you use software with higher minimum RAM requirements, such as Windows 2000 or Adobe PhotoShop, we expect that you would see much greater improvements by moving up to 128MB.

Get More From Your Laptop
If you've ever been frustrated by a lack of battery power in your laptop, a memory upgrade makes a lot of sense. Your system will be faster. Your battery will last longer. And you'll have more time to finish that next project before your battery runs low.

Top
Can you provide detailed instructions for taking apart my laptop?

Unfortunately, no. Because there are so many different kinds of laptops, we cannot provide detailed instructions for all of them. If you aren't sure how to find the memory slots on your laptop, we suggest you check the manual that came with your computer or contact the manufacturer. For information on how to put the memory module into the memory slot, see our Installation Guide.

Top