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High Performance DDR DIMMs
Ups and Downs or "how do I keep my stick happy?"
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(Review by MS, July 17, 2001)
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The Test Candidates, 256 MB Density
Unfortunately, Crucial told us that they didn't have any 256 MB DIMMs as review samples available, therefore we cannot cover those.
Corsair
The Corsair XMS 2400 DIMMs are available also in a true double-sided, 2 bank configuration with 16 chips.
All 8 positions on both sides of the PCB are populated with a total of 16 128 Mbit Micron chips and the module is rated to run at 150 MHz and CAS-2. The PCB appears to be the same as the one used in the 128 MB DIMMs
Infineon
Infineon is the first company to provide us with a sample based on 256 Mbi chips. This means that there are only 8 chips required for an overall module density of 256 MByte. In typical Infineon fashion, the latency specs are held extremely conservative specifying the DIMM as 2.5:2:2, an odd combination where the slowest part appears to be the Column Address Strobe (CAS) with 2.5 cycles whereas tRCD and tRP are specified as 2 cycles each
In order to achieve 256 Mbit density, Infineon had to increase the number of rows to 8092 (8k) while keeping the number of column addresses at 4096 (4k) which results in a total of 32 M addresses with 8 bits width.
Closeup of the 32Mx8 (256 Mbit) Infineon chip marked as -7 (143 MHz)
next page: => Converting Theory Into Practice, 128 MB DIMM performance =>
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