I think my DDR2-800 RAM is running at 400Mhz???

barfly · Post by **barfly** » Tue Jun 05, 2007 9:16 pm

I just put this new system together and according to CPUZ the memory is at 401Mhz, when its supposed to be 800. I don't understand why this is happening, i have memory set to auto in BIOS and its showing as DDR2-800. I'm have 2 GB of TWIN2X2048-6400C4 in dual channel. If anyone can explain why this is happening please respond.

InspectahACE · Post by **InspectahACE** » Tue Jun 05, 2007 9:27 pm

Mine does that too..in a way you have the answer to ur question within your question..im not exactly clear on this so bear with me..ur ram is running at 400mhz since it is in dual channel..you are getting 800 mhz...but essentially 400 per channel...i dont think that u get only 400mhz with one stick tho..i think you would the full speed in that scenario

camaroguy1998 · Post by **camaroguy1998** » Tue Jun 05, 2007 9:32 pm

DDR (Double Data Rate) Refers to an SDRAM memory chip that increases performance by doubling the effective data rate of the frontside bus.
400mhz x2 = 800mhz

barfly · Post by **barfly** » Tue Jun 05, 2007 9:55 pm

ok, so basically since its dual channel i'm actually getting 800 not 400, i guess that makes sense. thanks guys.

camaroguy1998 · Post by **camaroguy1998** » Wed Jun 06, 2007 1:06 am

barfly wrote:ok, so basically since its dual channel i'm actually getting 800 not 400, i guess that makes sense. thanks guys.

Dual Channel DDR and DDR2

Chipsets on the motherboard may support two independent memory controllers, which allow access to two memory modules simultaneously (upstream data on one 64-bit channel; downstream data on the other). Channels can be configured as two 64-bit or one 128-bit. Modules must be installed in matched pairs unless the chipset has an option for mismatched modules.

Basically Dual Channel(2 modules) memory is seen by the chipset and performs as 1 module!

prozac26 · Post by **prozac26** » Wed Jun 06, 2007 5:11 am

barfly wrote:ok, so basically since its dual channel i'm actually getting 800 not 400, i guess that makes sense. thanks guys.

Not quite dual channel.

The RAM has two cycles (upward and downward), and a single cycle runs at 400Mhz, when both cycles run, they add up to 800MHz effective speed. The correct way of saying that should be 400MHz, but everyone just mentions the effective speed.

You can have a single stick, and still get that, it's normal.

JohntechUPi · Post by **JohntechUPi** » Wed Jun 06, 2007 4:00 pm

This is a pretty good explanation of memory in general.
http://www.corsair.com/memory_basics/index.html