gecko said:
I used Everest to diagnose my system and I find the following under
Motherboard>SPD:
[ DIMM1: 1 GB PC3200 DDR SDRAM ]
Memory Module Properties:
Serial Number None
Module Size 1024 MB (2
ranks, 4 banks)
Module Type Unbuffered
Memory Type DDR SDRAM
Memory Speed PC3200 (200
MHz)
Module Width 64 bit
Module Voltage SSTL 2.5
Error Detection Method None
Refresh Rate Reduced (7.8
us), Self-Refresh
Memory Timings:
@ 200 MHz 3.0-3-3-8
(CL-RCD-RP-RAS)
@ 166 MHz 2.5-3-3-7
(CL-RCD-RP-RAS)
@ 133 MHz 2.0-2-2-6
(CL-RCD-RP-RAS)
Can someone give me a quick interpretation of the meaning of 'memory
timings' and '(2 ranks, 4 banks)' above? I am running with one
1024MB DDR in a motherboard with two slots, one empty.
Thanks
-GECKO
The SPD chip (a tiny chip on the module) is the source of that info.
The three sets of timing values shown, correspond to the ability of
that PC3200 module, to run at slower speeds when necessary.
The two rank thing, is actually a good thing. That is, if the determination
is accurate, and we cannot know that for sure.
A rank is enough chips to make a 64 bit wide array. The memory bus
is 64 bits wide. For example, if I took eight 8 bit wide chips, that
would be enough to make a single rank. I might put those eight
chips on one side of the module, making it easy to add a second
rank to the other side of the module.
Since you've got a dual rank 1GB module, that means it is a low
density module, and can work with the vast majority of DDR
motherboards. There are some modules on Ebay, which use sixteen
of the 4 bit wide chips, and that is a single rank. Intel
chipset datasheets specifically exclude modules like that,
so at least Intel doesn't like them. I did discover, that
the JEDEC standard covers them, and yet the companies that
make those (bad) modules, never put their name on the module.
It is like they aren't that proud of their handiwork.
The "4 bank" is a specification at the chip level. There are
two BA signals, allowing up to four banks to be addressed inside
the chip. Each bank can have an open page, which makes it possible
for more efficient memory access (the transaction is shorter, if
the page is already open). From a consumer viewpoint, this is
largely irrelevant.
If you had a dual channel motherboard, you might try to match
the module characteristics if buying another. If the
motherboard is a single channel variety, then you could
do whatever you wanted. If you somehow managed to purchase
a slower module than your current one, the BIOS picks
slow enough settings, such that all modules can operate
properly.
PC3200 3-3-3-8 might be considered to be "industry standard"
memory. If you forked out more money, enthusiast memory
would be 2-2-2-6. The difference might be a few percentage
points in a memory intensive application. I bought the
2-2-2-6 type, purely so I could benchmark both situations.
(I can set my BIOS to 2-2-2-6 or 3-3-3-8 and see what
difference it makes.) My DDR system is in semi-retirement,
so it isn't that easy to run off a benchmark at the moment.
Paul
