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Dual channel memory in a AMD/AM3 mobo does it work??

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wickedout

Member
Joined
Aug 14, 2009
Can you use dual channel memory on a AMD/AM3 mobo?

I was just wondering if you could or not. Anyone?
 

Neuromancer

Member
Joined
Oct 11, 2005
Location
Tau'ri
Yes, dual channel has been used on AMD platforms for years :)

If you are asking about DDR3 than yes if the motherboard is an AM3 socket (NOT AM3 compatible because many AM2/AM2+ socketes are AM3 compatible but do not run ddr3).

Next year (?) quad channel is coming out :) :) probably just be uber highend until 2011 though.
 
OP
wickedout

wickedout

Member
Joined
Aug 14, 2009
That's what I thought. Wasn't sure though.

Can't you use both dual and triple channel in AM2/AM3 mobos?

Quad memory? We both know it won't be cheap!

Thanks!
 

Neuromancer

Member
Joined
Oct 11, 2005
Location
Tau'ri
You can run 3 sticks but not in dual channel. So not recommended unless you only have 2x256MB sticks a nd a 512MB stick laying around, the 1GB of ram would be worth more performance wise than the bandwidth benefits you get from dual channel.

You can run 4 sticks in dual channel but is generally not considered for an enthusiast level rig as it puts more strain on the IMC and is harder to top out your ram with high speed or tight timings. You can not run 1066 DDR2 on AM2/+ sockets without overclocking the board limits you to a 800 MHz (effective) multiplier. But the almighty dollar is the decider here. If you have a 2x1 GB kit already picking up another 2x1GB kit is sometimes a financial option when selling your current kit and upgrading to a 2x2GB kit is not.

Effective is a key word also when determining speeds of memory. (And some other buses) DDR/DDR2/DDR3 sends 2 packets of data per cycle. So What is advertised as 800 MHz, 1600 MHz or 2000 MHz (effective) is actually running at one half that speed. (400/800/1000 actual)

So if you open CPUz to the memory tab and see that you are only running 800 MHz with a 1:4 divider on AM3 but have your RAM set to 1600MHz in the BIOS, that is correct.

200 MHz internal bus clock (HyperTransport reference clock) times 4 for memory clock yields 800 MHZ ram or 1600 MHz effective :)


The effective actual thing is probably due to consumers not understanding the correct annotation for memory which denotes bandwith. IE PC3200 = DDR 200 MHZ (400 MHz effective) (simply divide the PC/PC2/PC3 number by 8 to get the effective speed)
 
OP
wickedout

wickedout

Member
Joined
Aug 14, 2009
The reason I was asking is because I'm going to build a AMD rig for a family member.

Thanks again Neuro!