Dual channel 1066

[spac3d]

My friend wants to update his 1GBx1066 x 2 and put another 2 or 1 sticks in, making him have 2gb -> 4gb. I have told him about the limitation of only 1-channel of 1066. What exactly will happen if he puts more ram in the other slots (channels).

Will it stop working in dual channel mode, and will it be a hindering thing in performance?

Should he sell his 1066 DIMM slots and buy 4GB of 800?

[GT-R]

2x2g 1066mhz should be best for performance, dont know how much increased performance you get from dual channel vs single though.

[GheeTsar]

He's better off selling the 1066 and buying 2x2Gb 1066 sticks IMHO.

[Fraz]

He's better off selling the 1066 and buying 2x2Gb 1066 sticks IMHO.

Especially if he's using a p45 board.

[spac3d]

He has the M4N78 Pro, which I had and was super buggy with voltages.

I tried to put a Phenom 940 (Rated for it) and the voltage wouldn't go to 1.35v with a phenom in, but a 6000+ it would. Totally weird.

[GanjaM4N]

as long as the 2 other 1 gig sticks he puts in are 1066 they'll still run in dual channel (you can even mix sizes an still get dual channel) the main things the memory speed (tho using all identical sticks is prefered)

performance wise dual channel u will get more throughput out of the ram, dual channel in a sense makes ur 1066 ram run at 2132 since each channel has its own bandwidth

however one thing to remember is RAM and the CPU's FSB kinda work hand in hand, the CPU's FSB is the speed in which the CPU can send info to your ram, so if your ram is faster than ur FSB you won't notice much a dif, but if the RAM's slower you will, which is why dual channel was introduced. (to help memory keep up with the ever increasing FSB speeds)

here's an example....tho its probably kinda confusing lol

lets take a Core2Quad 2.6GHz with a FSB of 1333 OC'd to 3.2GHz with a 1600FSB, and using 1066 MHz memory
in single channel the FSB is faster than the ram since the ram only runs at 1066 and the FSB is 1600, therefor the CPU in a sense has to wait for the RAM since the CPU can Send info faster than the RAM can keep up, which will cause a slow down (tho not alot, since the ram is 1066, but if we were using 800 or 667 it would be even more noticable) - but in single channel mode you would need memory to run at 1600MHz inorder to keep up (or faster of course

now in dual channel mode 1066 memory in theory runs at 2132MHz (2 channels x memory speed) so now its reverse, the CPU can't keep up with the RAM (which is way better than the RAM not being able to keep up with the CPU) - however anything after the FSB speed doesn't amount to much in speed wise, so in theory a system with a 1600 FSB, will just about (tho not exactly) run just as fast on a system with dual channel 800MHz memory as it would with dual channel 1066MHz memory (since 800 in ddual channel is 1600MHz)


however this does not apply with the new versions of Intel CPU's (I3/I5/I7's) since they are no longer bottlenecked by the FSB Speeds, they use a new method of communicating with the system -i don't want to explain it all lol, but basically on old CPU's the CPU had to talk to the memory via the memory controller which was on the Mobo, so it was limited by the FSB of the CPU, now the memory controller is directly within the CPU which = way better access to the memory itself, and makes the new cpu's not limited by the FSB when it comes to memory.

for more info on the new I series CPU's google it lol or google QPI (which is basically the new method it uses, that replaces FSB

[Pob255]

Well as he's talking about an ati am2 system that's not very relavent, granted the new intel systems use a system simular to that which amd have used since the introduction of am2, ie intergrateing the memory controller into the cpu so it talks to the memory directly.

at the same time on socket 775 the cpu fsb, is not the true fsb as the memory controller is on the northbridge, the cpu fsb is "quad pumped" ie intel lists it as 4 time higher than that of the actual fsb.
So on a Core2Quad q8400 2.6GHz with a FSB of 1333 the actual fsb is only 333mhz and overclocked to 3.2GHz with a 1600FSB it's only 400mhz.
DDR2 also runs at half it's listed speed, so DDR2 pc2-8500 is actually running 533mhz.
So you could quite happly run ddr2 pc2-6400 (800mhz) ram quite happly on a q8400 oc'd to 3.2ghz at a 1:1 cpu:memory ratio without it having any major impact.

@spac3d, odd about that cpu, the asus cpu support list states, pcb version 1.01G and BIOS 0603 or better for full support.
Both the 940 and 6000+ are listed as 125w, ganted amd lists the 940 as 0.875V to 1.5V so it should be able to run.
I'd double check the BIOS and motherboard revision.(revision will be printed on it someware)

[DanceswithUnix]

Which CPU is he using?

Or more pointedly, when booting up does the BIOS say "unganged mode" for the DRAM?

Basically with the Phenom class CPUs I gather they usually drive the two ram channels independently so you no longer have the massive penalty you used to get if the RAM banks were not matched.

Matched banks will probably still give a better system, balance is always good.

Also some CPUs are better than others at driving a pair of dimms on a channel, so you might find a pair of 1066 sticks on the same channel are driven as 800 sticks.

This comes back to the earlier advice given by others, 2 X 2GB matched sticks will drive at full speed for any CPUs you might have.

[spac3d]

He's running a 6000+. I had to send my M4N78 Pro back and got a refund, because there is a bug within the bios (about 3 months ago) that won't run at the correct voltage.

I think I will advise him to sell his 1066 sticks and buy 2x2GB, but I have told him if he wants to see a big performance increase then it's CPU time.

[arthurleung]

There shouldn't be any penalty if he put 2x1GB in channel A and 1x2GB in channel B. There will be 2GB in each channel.

[DanceswithUnix]

He's running a 6000+. I had to send my M4N78 Pro back and got a refund, because there is a bug within the bios (about 3 months ago) that won't run at the correct voltage.

I think I will advise him to sell his 1066 sticks and buy 2x2GB, but I have told him if he wants to see a big performance increase then it's CPU time.

Interesting, unless overclocked I didn't think the 6000+ could do 1066 on the ram.