Ive just been studying about all the forms of SDRAM etc, and when it came to buffered/registered DRAM I found out that normal PC's usually have upto 4 slots for SDRAM, any more gives producers of motherboards lots of electrical problems. So to solve the problem of systems that require maybe 6, 8 slots, they require special DRAM, such as buffered/registered SDRAM. This SDRAM has a special buffering chip on the address bus added to it to work as an intermediary between SDRAM & North Bridge. To take advantage of buffered SDRAM, the motherboard and brige must be able to support SDRAM. Slots requiring buffered DIMMs are keyed differently then those requiring unbuffered DIMMS so it will be physically not possible to install these DIMMs into the slots short of shaving the key. Electrically, possibly, but you have to remember that the register drives the addressing unit on the DIMM and the bridge will likely not be designed to accomidate the drain required to directly drive the memory chips on the address bus and as such may cause instability if it works at all. In addition there is a single clockcycle delay from when the address is written to the registers to when the address is propigated to the memory, in such timing errors could arrise from a bridge expecting that delay.
- you cannot use unbuffered SDRAM on a motherboard that supports buffered memory, because the notches on buffered DIMMS are in different positions than for unbuffered DIMMS.
No you cannot the ECS P4VXASD2 supports the following:Two 184-pin 2.5V DDR SDRAM (DDR266/DDR200) Maximum: 2GB DDR or SDRAM (Buffered) / 1GB DDR or SDRAM (Unbuffered)
It is called an "unbuffered dimm"
Unbuffered DIMM.
Depending on the specs of the motherboard, a motherboard that supports ECC SDRAM may support a non-ECC SDRAM module. If a motherboard can support both types, you would have the option to enable or disable the ECC feature in BIOS. Other than the fact that an ECC module has an odd number of chips, there is no other physical difference on the module. They are keyed the same.
SDRAM has 168 pins and two notches on the module.
168-pin SDRAM DIMM
DIMM. Two types of DIMMs: a 168-pin SDRAM module (top) and a 184-pin DDR SDRAM module (bottom). Note that the SDRAM module has two notches (rectangular cuts or incisions) on the bottom edge, while the DDR1 SDRAM module has only one.
You're computer will require a "DDR2 SDRAM DIMM". DDR2 SDRAM is the type of memory you are after, it is also a DIMM. Most modern memory are all DIMM's (Dual inline memory module), much older ram were SIMMS (single ingline memory module). DIMM refers more to the physical make up of the module (DIMMS have contacts on both sides of the module). So any DDR2 SDRAM that you buy IS a dimm. You may want to look at the wikipedia page about DDR2 SDRAM at http://en.wikipedia.org/wiki/DDR2_SDRAM
By looking at the notch on the right
The notch on the right identifies the voltage used by the module.
A DDR SDRAM module
In SDRAM, rising and falling edges are the opposite edges of a memory module through which data can be transferred. SDRAMs that are designed this way are called DDR (double data rate) SDRAMs.