Asus AV8 Rev 2 Dual channel memory

[ikonia]

ok guys, looking for the voice of experience.

I have an Asus Av8 red 2 motherboard with an FX55 (I mention due to the memory controller on the chip)

According to the docs for the motherboard there are 2 sets of 2 dual channel sockets.

eg: Dim sockets 1 and 3 (light blue) are dual channel 1
Dim sockets 2 and 4 (black) are dual channel 2

The documentation on the motherboard suggets I can use all 4 slots in a "dual channel" configuration, as mentioned above (2x2)

Notes on other motherboards on the web suggest dual channel can only be used on 2 of 4 sim sockets, so as soon as you use 3 or 4 of the sockets instead of just the 2 dual channel sockets dual channel is "turned off"

Whats the correct info on this ?

can I use all 4 slots in a dual channel configuration ?
Will dual channel be turned off if I populate any / both of the other two free slots ?

The manual for the motherboard seems to suggest the opposite of the trends of motherboards.

thanks

[noah]

this may not be that much help, but i have an abit nf-7 using 3 sockets, 2*256 in the 'dual channel' sockets and 1*512 in the other socket, i thought it wouldnt run in dual chanel mode, but the post screen tells me it still is running the 2*256's in dual channel mode hopefully will be the same story with yours?

[ikonia]

thats a start and noted.

Be really interested in more info an experience off other users

[Olly1234]

From my undestanding the new A64 MB's support full dual channel while all four slots are populated (Due to the on-chip memory controller), however they will force you to run 2T instead of 1T which means that you take a fairly sizeable performance hit

[ikonia]

can you explain 2T and 1T - thats a new phrase on me.

I'm guessing you'd advise using no more than 2 slots if possible though.

[Olly1234]

This delay is between the sending of the Chip Select signal till the time the memory controller starts sending commands to the memory bank. The lower the value, the sooner the memory controller can send commands out to the activated memory bank and thus the faster your memory is

With 1T, the memory controller will only insert a command delay of one clock cycle

With 2T the memory controller will insert a command delay of two clock cycles

If the SDRAM command delay is too long, it can reduce performance by unnecessarily preventing the memory controller from issuing the commands sooner. However, if the SDRAM command delay is too short, the memory controller may not be able to translate the addresses in time and the "bad commands" that result will cause data loss and corruption...

Basically it seems to give you roughly about 10% difference in bandwith from some bench's I've seen..So yes you'd be better runing 2 x 512 modules really

[Steve]

The theory: It should work.

The fact: It doesn't always cooperate, depending on the memory you use.

[Olly1234]

Yep, some suggestion it's a design fault with the memory controllers, not able to run 1T with both chanels enabled

[ikonia]

excellent information. Great jobs chaps

[Steve]

Originally Posted by Olly1234

Yep, some suggestion it's a design fault with the memory controllers, not able to run 1T with both chanels enabled

Fault or limitation? Perhaps they weren't able to engineer it to control 4 modules at 1T.

Just a thouht from me, that's all.

[Olly1234]

Perhaps unintentional Limitation :-) Thats just some bits i've seen about it. I would have thought that it would have been sorted by now if it were minor, perhaps it'l take a revision of the whole memory controller to resolve it and AMD don't think it;s cost effective currently beings as most people who care about perfomance run 2x512 or 2 x 1gb while the masses don't know about timmings and buy from PC world anyhow

[Stompy]

It's A8V btw