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HOME  Memory #710 - Corsair Twin2X2048-8500C5 Memory
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#710 - Corsair Twin2X2048-8500C5 Memory |
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Written by Rodney Reynolds
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Friday, 04 August 2006 |
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Page 3 of 6
Specifications:
The speed on
this memory is 1066MHz DDR or PC-8500, it has a CAS of 5,
and a memory timing of 5-5-5-15
(CAS-TRCD-TRP-TRAS).
Now what does DDR and CAS mean?
DDR stands for Double Date Rate and that means it doubles
the bandwidth of the memory by transferring data twice as
fast on both the rising and falling of the clock cycle.
CAS stands for Column Access Select or Column Access Strobe
and that essentially means the number of cycles for the
memory to get information and then process that information.
Also keep in mind that a lower CAS is much better than a
higher CAS, so try and keep CAS as low as possible when
overclocking.
This memory is also Dual Channel which means better overall
memory bandwidth resulting in superior performance. In order
to benefit from this technology you will need to have a dual
channel motherboard. Non-dual channel motherboards do not
have two fully independent 64-bit memory controllers but
dual channel boards do, which means they have a 128-bit
memory interface. They can be installed singly, but
obviously performance will be much less at the same MHz.
This memory has something new and it's called Enhanced
Performance Profiles (EPP). This new memory standard was
jointly developed by Corsair and NVIDIA. Enhanced
Performance Profiles elevate memory performance by taking
full advantage of the additional memory parameters that are
now added to the unused portion of the JEDEC standard Serial
Presence Detect (SPD). As a new open standard, immediate
adoption by motherboard manufacturers and other memory
manufacturers is expected.
Currently EPP memory is only compatible with the nVIDIA
nForce 590 SLI chipset which is based on the AMD socket, but
soon Intel and others will follow suit. I suspect most
chipset manufacturers will adopt this new memory standard
soon enough.
Please remember that this memory is DDR2 and it does differ
from DDR memory in a number of ways. The following
explanation below goes over the general differences. It does
not take into account some of the fast DDR/DDR2 memory on
the market, but it is designed to help you distinguish
between the two:
To begin, the
maximum Data Rate is different (400MHz for DDR vs. 667MHz
for DDR2), Bus Frequency (200MHz vs. 333MHz), DRAM Frequency
(200MHz vs. 166MHz), Package Type (TSOP-II vs. FBGA),
Voltage (~2.5 vs. 1.8), Prefetch Size (2 bits vs. 4 bits)
and a CAS Latency (which varies quite a bit but in general
2.5 for DDR vs. 4 for DDR2 memory). The on-die termination
is different as well. To eliminate signal noise, DDR uses
transistors that are on the motherboard whereas for DDR2
it’s on each memory chip. The Off Chip Driver Calibration on
DDR2 memory also increases signal integrity.
While 240-pin DDR2, 184-pin DDR and the older style 168-pin
DIMM memory are all approximately the same size, the 240-pin
DIMMs and 184-pin DIMMs have only one notch within the row
of pins. The notch in a 240-pin DDR2 DIMM is slightly more
toward the center of the module. Please keep in mind that
DDR2 memory is not backward compatible and will only fit
motherboards specifically designed for it.
Detailed Specifications:
Speed: XMS28500 (PC2-8500) or DDR2-1000 (250MHz)
Size: 1024 x 2 = 2048MB kit
Configuration: 64MB x 8
Chip: Micron Rev D
Latency: 5-5-5-15
Package Type: 240 DIMM
Voltage:
2.2
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