Please help! Dual Channel DDR without new CPU?

[Inzite]

Hi,

I had just made up my mind to replace my not very good Asus P4S8X with an Abit IS7.
I have a P4 2.4 GHz 533 MHz and 2 x 512 MB DDR2700 TwinMOS.
Of course I understand that I can't fully utilize the motherboard because I don't have a 800 MHz-processor.

The memory should be able to do 400+ MHz DDR though, with loose timings.

Well, on to my question. I was reading some reviews of this motherboard when I stumbled across this one:
http://www.ocaddiction.com/reviews/mobos/abit_is7/page2.shtml

"Dual Channel DDR400 support only with 800MHz FSB CPUs"

That sounds like I can't run my memory in dual channel without the new 800 MHz processor. Is it that bad?
Or do they simply mean that if I run 1:1 on FSB/memory, it isn't possible to run at DDR400 speeds with an older processor?
I find if very strange (and sad) if you can't run in dual channel mode if you don't have a 800 MHz processor...

Please help me shed any light over this!

/Jan

 

[tabytha77]

You, sir, are correct.

<A HREF="http://ftp://ftp.abit.com.tw/pub/download/manual/english/is7.pdf" target="_new">http://ftp://ftp.abit.com.tw/pub/download/manual/english/is7.pdf</A>

 

[Crashman]

Nononononono

You can run your RAM at PC2100 dual channel speed on that board. In fact, you can overclock from there!

You simply can't run at PC3200 speed with a 133MHz (QDR533) CPU bus. That would require a higher memory ratio than what's available, in fact that ratio would be 3:4 CPU:RAM.

So yes, they simply mean that you can't run dual channel at a ratio of faster than 1:1.

NO! YOU CAN RUN DUAL CHANNEL!

Grr, you repeated yourself too many times. The best setting for your CPU on that board is dual channel and 1:1. It will work with your CPU and your memory. In fact, since your memory will be underclocked, you should be able to use the fastest timings!

Don't worry about your memory running at the slower speed, since you'll have dual channel, it will still be faster than on your current board! Think about it this way, PC2100 speed (133MHz, aka DDR266) in dual channel mode has the same bandwidth as PC4200 (DDR533, which doesn't exist) in single channel mode!

So simply the answer is yes, you can run in dual channel mode.

No, you can't run in dual channel PC3200 mode with your "533" bus CPU, but running your ram "in sync" with your CPU is a better idea anyway, considering the "dual channel" mode makes up the bandwidth.

Dual channel DDR266 has better bandwidth than single channel DDR400. And it's "in sync" with your CPU bus, so the memory controller can operate at peak efficiency.

Do you like to overclock? Because overclocking your bus speed to 166MHz will yield a CPU bus of QDR666 (as oposed to the stock 533) a CPU clock speed of 3.0GHz, and a memory speed of PC2700 (166MHz, aka DDR333). Which would be perfect for your RAM, as long as the CPU can go that high.

Further, PC2700 in dual channel mode would have the equivelent bandwidth of memory twice as fast in single mode (PC5400!).

<font color=blue>Watts mean squat if you don't have quality!</font color=blue>

 

[Crashman]

Quit confusing people, the truth is confusing enough without telling them such things as their board won't run in dual channel mode. It will run in dual channel mode, it just won't run in dual channel mode with a higher than 1:1 ratio!

<font color=blue>Watts mean squat if you don't have quality!</font color=blue>

 

[Inzite]

Thank you Crashman!
I'm off to order then.

 

[tabytha77]

Ouch! My mistake! Check this out:

<A HREF="http://fae.abit.com.tw/eng/faq/qa/2003/2003043001.htm" target="_new">http://fae.abit.com.tw/eng/faq/qa/2003/2003043001.htm</A>