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4.4 Memory

Read this great thread on how to maximize all of your RAM.

by onavi See Profile edited by vkr See Profile

As a general rule, it is best to match the type of memory that is currently in your system. However, it is possible to mix and match SDRAM speeds under certain conditions.

You CANNOT add slower modules to a system designed for faster modules. For example, you cannot add 66MHz modules to a system designed for PC133.

You should NOT use a PC133 or PC100 with a 66MHz front side bus system. You should only use 66MHz memory modules with a 66MHz front side bus system.

You CAN use PC133 modules with a 100MHz front side bus system and vice versa. However, keep in mind that your memory will only be as fast as the slowest "link" in the system. If you install PC133 modules with a 100MHz front side bus or PC100 modules with a 133MHz front side bus, your memory will only run at 100MHz

by Cariad See Profile
last modified: 2002-08-26 11:09:37

First check to make sure one of the memory sticks hasn't been un-seated.
If you have recently installed memory, again, check it is tightly in place.
If all memory is seated properly,and you're still getting the error, enter the computer CMOS and ensure that the CMOS memory settings are properly set for the amount of memory you have in the computer. Failing this, it is possible you might have some bad memory.

by Cariad See Profile edited by vkr See Profile

72 bit memory is commonly known as ECC memory. It has an additional 8 bits for Error Correction Check. 64 bit memory is non-ECC (Non- Parity). 72 bit or 64 bit configuration are typically found in 168 pin DIMMs

reference

by Cariad See Profile edited by vkr See Profile

CL stands for CAS Latency. It is a programmable register in the SDRAM that sets the number of clock cycles between the issuance of the READ command and when the data comes out. Smaller number for CL indicates faster SDRAM within the same frequency.

reference

by Cariad See Profile edited by vkr See Profile

CL2 parts process data a little quicker than CL3 parts in that you have to wait one less clock cycle for the initial data. However, after the first piece of data is processed, the rest of the data is processed at equal speeds. Latency only affects the initial burst of data.

Once data starts flowing, there is no effect. Bear in mind, a clock cycle for a PC100 module is 10 nanoseconds so you probably won't notice a significant performance difference.

Most systems will accept either latency part. However, there are some systems that require either CL2 or CL3 parts.

reference

by Cariad See Profile edited by vkr See Profile

It means you may experience system errors in a 100mhz system because the memory's performance cannot keep up with the system requirement. The system will operate at the speed of the slowest component. For example, installing 66MHz SDRAM memory in a PC-100 system will cause the bus to operate at 66MHz, rather than the speed it was designed to operate at.

reference

by Cariad See Profile edited by vkr See Profile

Mac Quadra 700, 900, 950, and MacIntosh II series computers use 30 Pin SIMMs. Installation requires 4 SIMMs per bank of the same value.

Mac IIfx uses 64 Pin SIMM modules.

Mac Plus, Mac SE, Mac Classics, Classic II, Color Classic, Mac LC, LCIII, Performa 200,400, 405, 410, and 430 utilize 30 Pin SIMMs.

New Quadras, newer Performas, and Centris series utilize 72 Pin SIMMs.

Most MacIntosh computers come with onboard permanent memory and can utilize 72 Pin SIMMs 1 at a time.

Mac Performa 6400/180 & 200 models require 168 Pin DIMMs to upgrade.

Memory Type: Fast Page Mode DRAM

reference

by Cariad See Profile edited by vkr See Profile

DIMM stands for dual inline memory module, and SIMM stands for single inline memory module. The gold or tin pins on the lower edge of the front and back of a SIMM are connected, providing a single line of communication paths between the module and the system.

The pins on a DIMM are not connected, providing two lines of communication paths between the module and the system, one in the front and one in the back.

SIMMs and DIMMs are not interchangeable; they are different sizes and they install into different types of sockets.

reference

by Cariad See Profile edited by vkr See Profile

Crucial(a division of Micron)

Mushkin

Cosair

Samsung

by dragon See Profile edited by vkr See Profile

66MHz, PC100, and PC133 are three different speeds of SDRAM (synchronous dynamic random access memory) modules. Of the three, PC133 modules are the fastest, and 66MHz modules are the slowest.

by Cariad See Profile
last modified: 2002-08-26 11:08:38

RDRAM (Rambus dynamic random access memory) and SDRAM (synchronous dynamic random access memory) are two different types of memory technology. RDRAM is newer and in some cases faster, but SDRAM is less expensive.

The most important thing to know is that you cannot use RDRAM in a system designed for SDRAM or vice versa. The two types of modules are different sizes and shapes, so they won't even fit into the same memory slots. You should buy whichever memory type was designed for your system.

by Cariad See Profile edited by vkr See Profile

PC600, PC700, and PC800 are three different speeds of memory available for RDRAM (Rambus dynamic random access memory) modules. Of the three, PC800 modules are the fastest, and PC600 modules are the slowest.

Which type is right for you?
As a general rule, it is best to match the type of memory that is currently in your system. However, it is possible to mix and match RDRAM speeds under certain conditions.

You CANNOT add slower modules to a system designed for faster modules. For example, you cannot add PC600 modules to a system designed for PC800.

You CAN add faster modules to a slower system, but there is no real benefit to doing so. For example, you can add PC800 modules to a system that was designed for PC600 modules, but your memory will not get any faster as a result. If you want your system to be faster, you should add more megabytes of memory.

by Cariad See Profile edited by vkr See Profile

Registered modules contain a "register" that helps to ensure that data is handled properly. Unbuffered or standard memory modules do not have a register. Because registered modules are slower than unbuffered modules, registered modules are generally used only in mission critical machines, such as the large servers used by corporations.

Registered and unbuffered modules cannot be mixed in the same system.

by Cariad See Profile edited by vkr See Profile

ECC stands for "error correcting code." Like parity memory, ECC memory detects and reports memory errors. However, while parity can only detect errors, ECC can actually correct errors without interrupting the other operations of your system.

If you do not see an option for ECC memory when searching for your memory upgrade, your system most likely has non-ECC memory installed and will not support ECC memory. In this case, you should upgrade your system with non-ECC memory (standard).

If your system has ECC memory, you should choose the upgrade option with "w/ECC". If you determine that your system is using non-ECC (standard) memory, you should select the upgrade without ECC in the description.

There is a slight decrease in performance, but it's usually approximately 3-4% on PC133 CAS2 ECC SDRAM insignificant since 3% is barely within the margin of error on benchmarks

ECC more expensive than Non-ECC, but not all motherboards support ECC ram. check with your Motherboard manufacturer before purchasing Ecc Memory. It's often used in high end systems, or servers.

by Cariad See Profile
last modified: 2002-12-28 17:21:57

Crucial has made it pretty easy to find out what memory should be used in your system. However, if you don't know what system you have, or the make of your motherboard and are comfortable with looking inside your pc, do the following.

You can tell which kind you have by looking at one of the modules currently in your system. Count the number of black chips on one module. If the number of chips can be evenly divided by three or five, you should buy ECC or parity (whichever is offered for your system). If not, you should buy non-parity.
For example, if one of your modules has nine chips, you should buy ECC or parity. If one of your modules has eight chips, you should buy non-parity.

by Cariad See Profile

There is a common misunderstanding that Windows 98/98SE can't/won't work on a system with more than 512mb of system RAM.

Without some specific tweaks, this is true!
To tweak your system to handle more than 512mb of RAM (only if you're using Windows 98/98SE !),
see this Microsoft Knowledgebase article

by dbmaven See Profile

The page at the link below has pictures and textual information that will help you to identify the type of memory your system uses.

»stores.ebay.com/AquaDuston-Elect···sQQtZkm?

Feedback received on this FAQ entry:
  • Site no longer exists

    2010-12-05 06:54:17



by MrFixitCT See Profile edited by dbmaven See Profile
last modified: 2005-08-21 20:18:35