DDR2 & DDR3 in Motherboard Specs ... Aren't DDR2 and DDR3 keyed differently

[DaveLembke]

DDR2 & DDR3 in Motherboard Memory Support Specs ... Aren't DDR2 and DDR3 keyed differently to disallow use of DDR2 into a DDR3 slot etc?   

I have seen some boards from asrock that allow DDR2 and DDR3 but it has both DDR2 and DDR3 memory slots. This one only has what looks like DDR3 slots.

I looked at the specs here to see if they have a 1600Mhz DDR3 list of supported RAM because I have a 8GB Stick to use. Motherboard calls for 1333Mhz which is all the memory controller will run at. And it looks like the 1600Mhz DDR3 stick should underclock to 1333Mhz. But the DDR2 listed as supported caught my attention. I havent seen any DDR2 with the same keying as DDR3 as well as I am not aware of a DDR2/DDR3 optional RAM slot. 

http://www.biostar.com.tw/app/en/mb/introduction.php?S_ID=856#memorysupport

[BC_Programmer]

They are keyed differently. I took a picture of some of the RAM modules I have. (Top to bottom: DDR3, DDR2, DDR, SD-RAM, EDO)

My understanding is that boards that claim to support both would have separate slots for each. Similar to how some motherboards supported both SDRAM as well as EDO RAM SIMMs.

I think the Memory support for that might be referring to the chipset/Memory controller support? The specs at the top of the page specifically mention "Support 2 DIMM of DDR3 1333MHz up to 32G maximum capacity" with no mention of DDR2. Or perhaps the memory support is listed for a wider model set where some models have different module slots?

[patio]

Look at the board...that'll tell you...
Many board manuf's advertised it as a selling point...but the board didn't support it.

[Computer_Commando]

If it's 1333, it can't be DDR2 which had a max of 800.
If it's USB3.0, it also must be DDR3.
The overview tab says:  2 x DIMM DDR3-1333 Slots
The Manual is for both A5745-IBS & A5545-IBS.zip
The Memory Support tab says:  This is not a full listing but a memory guide used for testing.
The Manual indicates your 8GB Stick will work.
http://www.diffen.com/difference/DDR2_vs_DDR3

[DaveLembke]

If it's USB3.0, it also must be DDR3.

Interesting... Never picked up on this relationship. I know that some boards that require DDR3 dont have USB3.0 ports such as the Biostar A960D+ board that i have a FX-8300 8-core 3.3Ghz in, but never knew that if a board actually has USB 3.0 ports that the memory for that board would be DDR3 only. 

I wonder if a build with DDR2 would be a bottleneck for USB 3.0 communications if someone added on a USB 3.0 card to a PCI Express slot.

Currently using the USB 3.0 port on this new build and getting like 65MB/s max speed with 55MB/s average. Bought a new 4TB WD external for $109.99 so I can backup 450GB of my steam games off of an old 500GB Maxtor SATA2 Drive that has quite a lot of hours of operation on and isnt the most trusted drive I have as for I have seen many Maxtor drive failures. This one is very noisy with loud chatter when data is read/written and the case amplifies the chatter sound of the arm moving. Not a very graceful quiet design but I cant complain much since I got this 500GB for free.

I like the detail view with graph that Windows 10 has for data transfers to see speed of transfer etc. Im finally coming around to accepting Windows 10 



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[BC_Programmer]

I suspect it's not a direct relationship where one technically requires the other in some way, but rather like how a motherboard with DIPP memory won't have an AGP slot or a motherboard with SDRAM won't have a thunderbolt port- One or the other tech was "too dated" to be applicable when the other was implemented. There may be some constraints between one or the other I'm not considering but you can add USB 3 to a system using DDR2 with an expansion card so I'd think it was just a motherboard chipset design decision.

And if you want to be pedantic, "If it's USB3.0, it also must be DDR3." isn't true on it's own either now that there is DDR4 (of course in context it meant between DDR2 and DDR3)


Also worth taking note of is that the new copy dialog is actually from Windows 8.

[Computer_Commando]

I suspect it's not a direct relationship where one technically requires the other in some way...One or the other tech was "too dated" to be applicable when the other was implemented.

There may be some constraints between one or the other I'm not considering but you can add USB 3 to a system using DDR2 with an expansion card so I'd think it was just a motherboard chipset design decision...

Exactly! 
BTW, I've added 3.0 expansion cards; they're maybe 50% faster than onboard 2.0.

With onboard (integrated) 3.0, this is the transfer speed with Macrium Reflect (SSD to USB3.0 portable drive):
I/O Performance:  Read - 2.5 Gb/s, Write - 795 Mb/s