Resolved DDR400 becomes DDR333

This is an old PC but working fine. There are 2 pieces of 1GB DDR400 SIMM RAM on the motherboard. During cold boot, the RAM speed is reported as 400 MHz, but when the 3rd 1GB DDR400 SIMM RAM put on the remaining slot then when cold boot again, the RAM speed is reported as 333 MHz.

I thought the new inserted RAM was slow. But after I swapped them randomly on the motherboard, the results were the same:

2GB no matter which 2 SIMMs, the speed is 400 MHz;
3GB on the motherboard, it must be 333 MHz,

Why?

 

Hi, Ivan.

I'm afraid we may not have enough information to provide a meaningful answer.

Please enter your System Details. Those details might help us answer your questions.

 

Without knowing your system specs, I'm guessing your motherboard might automatically run the memory at 333MHz when you have 3GB installed. In other words, I think it might be a limitation of your motherboard.

See this other thread. The OP's mobo manual states,

I suspect Dakota's mobo would automatically switch to 333MHZ if (s)he installed an extra RAM stick even if all three sticks are rated 400MHz.

 

Thanks!

Took a couple hours poking around in my brain to recall the details of that discussion. I initially thought the issue might be RAM latency/delay timing settings in the BIOS and I was reading about those settings in my own mobo manual when my brain suddenly switched gears.

Even so, I had to re-read that other thread I mentioned above, re-download that mobo manual, and re-check it to be sure what I thought seems true (and so I could quote the manual for verification that others might seek).

Hopefully Ivan will check his own mobo manual, confirm our suspicions, and mark this thread resolved.

 

Thank you mailman and PeteC for your info. I thought it's the motherboard limitation too, thought the manual didn't give a clue of it. However, I entered the CMOS during boot up and found that even though I changed the RAM speed to 400 (while CPU clock speed was 200 MHz) and saved it, the next time I booted up and the RAM speed still returned to 333 as well as appearing in the CMOS.

 

Thank you for reporting back, Ivan.

I just looked in my own "old mobo" manual and found a similar limitation. (That's why I have only 2x1GB of PC3200 (400MHz) RAM. Due to the wording in the manual, I never even considered installing a third stick for fear I might damage something.)

ASUS A7V600 Motherboard Manual:
========================

Page 1-7 (Section 1.4.1 Core Specifications)

• DDR DIMM sockets.
  

Page 1-13 (Section 1.9 System memory)

and then half-way down the page there is a note,

Therefore I suspect I would run into the same issue as you if I chose to place 3x1GB PC3200 (400MHz) sticks in my mobo.

Thanks again for following up, marking this thread resolved, and providing a learning experience for all of us.