Member_2_23522
asked on
DDR2 Memory Compatibility
I'm building an Intel based desktop and am not sure what speed of memory I should use. Here are the basic specs:
Motherboard: Intel D945PVS (945P Chipset)
CPU: Pentium D 940 3.2 GHz 800 MHz Bus
The memory spec on the motherboard supports DDR2 667, DDR2 533 or DDR2 400 MHz SDRAM DIMMs. When I put these specs into Intel's barebones selector guide (http://indigo.intel.com/mbsg/Default.aspx) it comes back with "Dual Channel DDR2 400/533". My understanding is that the memory must run at least as fast as the system bus (800 MHz). I think this boils down to my lack of understanding of DDR2, but here are my questions:
1. Is this memory really operating twice as fast as the name, thus the "2" in DDR2? i.e. DDR2 400 is running at 800 MHz...
2. Why is DDR2 400 also listed as PC2-3200, DDR2 533 as PC2-4200 and so on?
3. Why is DDR2 667 (PC2-5300) not an option here according to intel?
4. Any general vendor recommendations for memory?
Thanks for your help.
Motherboard: Intel D945PVS (945P Chipset)
CPU: Pentium D 940 3.2 GHz 800 MHz Bus
The memory spec on the motherboard supports DDR2 667, DDR2 533 or DDR2 400 MHz SDRAM DIMMs. When I put these specs into Intel's barebones selector guide (http://indigo.intel.com/mbsg/Default.aspx) it comes back with "Dual Channel DDR2 400/533". My understanding is that the memory must run at least as fast as the system bus (800 MHz). I think this boils down to my lack of understanding of DDR2, but here are my questions:
1. Is this memory really operating twice as fast as the name, thus the "2" in DDR2? i.e. DDR2 400 is running at 800 MHz...
2. Why is DDR2 400 also listed as PC2-3200, DDR2 533 as PC2-4200 and so on?
3. Why is DDR2 667 (PC2-5300) not an option here according to intel?
4. Any general vendor recommendations for memory?
Thanks for your help.
SOLUTION
membership
This solution is only available to members.
To access this solution, you must be a member of Experts Exchange.
ASKER CERTIFIED SOLUTION
membership
This solution is only available to members.
To access this solution, you must be a member of Experts Exchange.
SPD is an industry standard these days as motherboard bios setup the ram settings automatically from this. I would be surprised if a memory module manufacturer does not have this capability in there modules.
ASKER
The recomendations I've seen for memory speeds all seem to say that one step up from the matched root clock is the way to go. This system clock is running at 200MHz (quad pumped) which would match DDR2 400, but this would actually be slower than DDR 400 due to the latency of DDR2. It also seems DDR2 667 doesn't help that much because at that point it's really diminishing returns unless I could get to DDR2 800 (which I can't). So DDR2 533 MHz seems the best choice. Does that make sense?
One last point....should all of these DIMMS support the Serial Presence Detect data structure? I'm guessing they do in order to be fully compliant with the DDR SDRAM specs, but none of the descriptions I read actually say this. Is this just a given?
Thanks again.