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Intel's Strike Force: 19 DDR-Motherboards With 845 Chipset and DDR-Support

Memory Matters: Why It Should Be DDR

RDRAM in the current PC800 standard will be replaced soon, as the performance benefits in contrast to DDR memory are gone. DDR-based chipsets like the VIA P4X266A, the SiS645 (this one even at 166 MHz memory clock) or the i845 offer similar or equal performance at reduced costs with respect to both the chipset and the memory.

In a few months, Intel will be offering the Pentium 4 for 533 MHz FSB . Simultaneously, a new RDRAM standard will appear (PC1066 at 533 MHz double-pumped), working perfectly synchronously with the clock speed. The first benchmarks proved that the team consisting of RDRAM + Pentium 4 makes much more sense than most of us imagined, and that common systems with DDR memory lag a bit behind. In this context, I would like to underline that we are talking of a price segment that is clearly higher than the one represented by these 19 motherboards. Both the new CPUs (2.4+ GHz) as well as the chipset and the memory will be available at lunatic prices. Only fat wallets, please.

So get ready for DDR as the old and new alternative! Though dual-channel PC1066 RDRAM will be quite a bit ahead of DDR memory, the latter will finally also work synchronously with the FSB. But DDR clock speeds could also be soon increased, bringing systems with 166 (DDR333) or even 200 MHz (DDR400) memory clock (double-pumped, of course).

RDRAMDDR-SDRAM
Clock400 MHz (double-pumped)133 MHz (double-pumped)
Name of moduleRambus Inline Memory Module (RIMM)Dual Inline Memory Module (DIMM)
Interface16 Bit64 Bit
Accessvia a dedicated protocolvia classic memory grid
Bandwith2 Byte (16 Bit) x 800 MHz= 1600 MB/s8 Byte (64 Bit) x 266 MHz= 2133 MB/s
Bandwidth in real life3.2 GB/sDual-Channel PC800 RDRAM2.1 GB/sPC2100 DDR-SDRAM
ECC available?yesyes
Largest module available512 MB1 GB
UsageTwo RIMMs only. Empty slots have to be equipped with continuity RIMMs.single
Performance DifferencesYes, 35 and 40 nsyes, due to several memory parameters (e.g. CAS Latency)
Memory manufacturing costsmediumlow
Motherboards manufacturing costsmedium to lowmedium to low
PlatformsIntel Pentium III, Pentium 4Intel Celeron, Pentium 4, Pentium IIIAMD Duron, Athlon, Athlon XP, Athlon MPVIA C3

From the table above, you can tell that there are several advantages of DDR memory:

  • Better upgradeability: single DIMMs can be added
  • Availability on all platforms: when changing to an Athlon XP system, you can continue using your DDR memory
  • Larger modules allow larger maximum memory sizes