| #710 - Corsair Twin2X2048-8500C5 Memory |
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| Written by Rodney Reynolds | ||||||||
| Friday, 04 August 2006 | ||||||||
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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