Question regarding dual channel memory in Nforce boards

[Cancer12]

I've got a pretty cool question regarding the dual channel capacity of Nforce motherboards. I have 2 sticks of DDR2100 ram. Running dual channel, they theoretically give 4.2 GB data to the cpu right? In that case, can I simply overclock the processor and leave the memory alone with the same effect of running both FSB and memory in sync? The overclocked processor should have all the bandwith it needs at a pretty high FSB. Is this the case?

 

[squidman]

Naw dude. It shall have UP TO 4.2 if u're using built in IGP. Sides that - its just like your "usual" memory, with 2.1 max throughput. Naw, i would overclock the FSB, so the CPU and mem run in sync. I got some kick ass results.
:beer: Cheers!

 

[squidman]

Think bout it: if nForce gave 4.2 when AGP card was used, would ANYBODY buy Intel? MArketing gimmick.

 

[Cancer12]

Oh, so its only dual channel when running with the IGP? I remember reading somewhere that it was always but the Athlon could only use as much memory as its FSB could use, voiding any performance gains

 

[Cancer12]

Got a link backing it up now

http://www.tomshardware.com/motherboard/20020716/nforce2-04.html

 

[charlie21]

Originally posted by: Cancer12
I've got a pretty cool question regarding the dual channel capacity of Nforce motherboards. I have 2 sticks of DDR2100 ram. Running dual channel, they theoretically give 4.2 GB data to the cpu right? In that case, can I simply overclock the processor and leave the memory alone with the same effect of running both FSB and memory in sync? The overclocked processor should have all the bandwith it needs at a pretty high FSB. Is this the case?

The bandwidth would be there, but the timings would still be asynch. Asynch = latency = bad. Really good idea, though!

 

[Cancer12]

What kind of performance difference would there be? I'd buy better memory at a later date to run it in sync

 

[Lord Evermore]

The IGP makes use of the extra bandwidth when you use dual channel. You can use dual channel with the SPP, but it doesn't provide much performance gain (essentially only DMA accesses from a hard drive or other PCI device would use the bandwidth, and those usually aren't a significant drain so they don't take too much bandwidth away from the CPU).

There can be several percentage points of performance drop using memory at a different bus speed than the CPU. It depends on whether you have applications that are affected by latency much. If you were able to get a significant overclock out of the CPU, the overall performance could probably make up for any latency penalties from asynchronous operation, but unless you're getting up to like a 166MHz FSB while using PC2100, then it's probably best to just try and overclock them both to the same speed, stopping at whatever highest speed the memory can handle without changing memory timings.

If you have a 266MHz bus CPU now, then just start saving up your money to get a 333MHz bus CPU and PC2700 (or better) memory at the same time.