What are the requirements for two RAM chips to run in dual-channel?

**ssj4Gogeta** · 08-13-2008, 08:19 AM

Hi

I have 2x1gig RAM, and both are DDR2 667MHz with same latencies. They aren't from the same company, but they run in dual-channel mode.

My friend has an old computer, and he was running 256 MB, until he recently added one more 256MB DDR stick. They aren't running in dual-channel mode, and he also seems to have a divider set.

The sticks seem to be running at 133MHz (rated). While his FSB is 400MHz. Please advise how he can run his sticks at full 100MHz unrated and in dual-channel (if possible). His vendor said he can replace the stick he just bought (it's in slot#2).

Also, one question: In the first image, are the listed RAM speeds rated or unrated?

**belfasteddie** · 08-15-2008, 09:07 AM

DDr will not run in dual.

HawMan · 08-15-2008, 10:03 AM

It will, but i heard you need a CPU FSB of 800MHz ( Dont quote me on this though ).

You need the Same Sticks of RAM ( Same Speed, CAS timings etc ). The reason they arent running in Dual is because one is 166mhz and the other is 133mhz.

Also, The Speed of the RAM will automatically reduce to the speed of the lowest stick.

Example - DDR 400 and DDR 333 - The DDR 400 (Which is the fastest ) Will reduce to 333mhz .

**ssj4Gogeta** · 08-15-2008, 10:53 AM

Thank you, belfasteddie and HawMan. I appreciate your help. He just got a 512 MB stick instead, so that he can later upgrade to 1gig.

@HawMan: No, it isn't required for the FSB to be 800. I have a 533 CPU and I run 2x 1gig sticks in dual channel.

08-13-2008, 08:19 AM	#1 (permalink)
ssj4Gogeta Custom User Title Join Date: Dec 2007 Location: India Posts: 1,867 OS: Windows XP SP2, Vista, Ubuntu Intrepid Ibex, Leopard (Kalyway) My System	What are the requirements for two RAM chips to run in dual-channel? Hi I have 2x1gig RAM, and both are DDR2 667MHz with same latencies. They aren't from the same company, but they run in dual-channel mode. My friend has an old computer, and he was running 256 MB, until he recently added one more 256MB DDR stick. They aren't running in dual-channel mode, and he also seems to have a divider set. The sticks seem to be running at 133MHz (rated). While his FSB is 400MHz. Please advise how he can run his sticks at full 100MHz unrated and in dual-channel (if possible). His vendor said he can replace the stick he just bought (it's in slot#2). Also, one question: In the first image, are the listed RAM speeds rated or unrated?

08-15-2008, 09:07 AM	#2 (permalink)
belfasteddie Enthusiast Join Date: Aug 2007 Location: Belfast N.I. Posts: 1,551 OS: Puppy Linux 4.12	Re: What are the requirements for two RAM chips to run in dual-channel? DDr will not run in dual.

08-15-2008, 10:03 AM	#3 (permalink)
HawMan Liam Join Date: May 2006 Location: Edinburgh, Scotland Posts: 2,941 OS: Win XP My System	Re: What are the requirements for two RAM chips to run in dual-channel? It will, but i heard you need a CPU FSB of 800MHz ( Dont quote me on this though ). You need the Same Sticks of RAM ( Same Speed, CAS timings etc ). The reason they arent running in Dual is because one is 166mhz and the other is 133mhz. Also, The Speed of the RAM will automatically reduce to the speed of the lowest stick. Example - DDR 400 and DDR 333 - The DDR 400 (Which is the fastest ) Will reduce to 333mhz . __________________ Please Consider Donating to keep the site free.

08-15-2008, 10:53 AM	#4 (permalink)
ssj4Gogeta Custom User Title Join Date: Dec 2007 Location: India Posts: 1,867 OS: Windows XP SP2, Vista, Ubuntu Intrepid Ibex, Leopard (Kalyway) My System	Re: What are the requirements for two RAM chips to run in dual-channel? Thank you, belfasteddie and HawMan. I appreciate your help. He just got a 512 MB stick instead, so that he can later upgrade to 1gig. @HawMan: No, it isn't required for the FSB to be 800. I have a 533 CPU and I run 2x 1gig sticks in dual channel.