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What every programmer should know about memory, Part 1

What every programmer should know about memory, Part 1

Posted Sep 21, 2007 23:00 UTC (Fri) by jwb (guest, #15467)
Parent article: What every programmer should know about memory, Part 1

Very nice article. You did address power issues obliquely when talking about DDR3, but I'm surprised you didn't mention the power drawbacks of FB-DIMM. The fast shift register on each DIMM requires a few watts more than a standard DDR2 module. And when you add more DIMMs to an FB-DIMM system, all memory access becomes slower, not just access to DIMMs at the end of chains. For example on a particular system I have here memory performance is best with 4 FB-DIMMs and a bit slower with 8.

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What every programmer should know about memory, Part 1

Posted Sep 23, 2007 8:23 UTC (Sun) by TRS-80 (guest, #1804) [Link]

AMD's next server socket will put four buffers per socket on the motherboard and otherwise use regular DDR3 DIMMs. Which is kind of like the external memory controller scenario, but connected direct to the CPU. Intel is rumoured to be developing something similar called AMB2.

What every programmer should know about memory, Part 1

Posted Sep 25, 2007 14:10 UTC (Tue) by wretcheddawn (guest, #47780) [Link] (1 responses)

Where do you find these 69 pin fb-dimms. It looks like everything I can find on newegg is 240 pin fb-dimms?

FB-DIMM pins

Posted Oct 4, 2007 20:16 UTC (Thu) by anton (subscriber, #25547) [Link]

Actually only the interface at the memory controller is 69 pins (allowing more channels from one memory controller chip). The FB-DIMM needs these 69 pins, plus 69 pins to talk to the next FB-DIMM, plus additional pins for power and ground; that's why they have the familiar 240-pin form factor.


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