Memory speed is not what it should be

[detoam]

Hi there!
I have a DDR2 400Mhz dual-channel 64 bit memory. But when i check the memory only runs at 200Mhz. Why? And how can I change that. I have tried setting it through BIOS, but when I input that it is DDR2 400 it still only goes at 200. I have overclocked my CPU to go at 260 and the memory changed to go at 260 as well. I am using ASUS M2A-VM if it matters.

 

[Matthew DeCarlo]

I assume your RAM is DDR2 with the marketed theoretical speed of 800MHz and your FSB:RAM is 1:1. With that assumption, it's safe to say this: your RAM is running not only at it's rated speed, but it's running faster (around 1,038MHz).

For some reason, on some systems the RAM frequency is reported at 1/4th the marketed frequency, rather than the 1/2 denomination which appears to be more common.

So if your RAM is rated for 800MHz, it's true clock frequency is 200MHz, you're running it at 259.7 (259.7 x 4 = 1,038.8). What I am suggesting here is supported by the fact that your FSB is also at 259.7MHz x 11 = 2,856.7MHz (your CPU's core frequency).

My main PC does the same thing. My RAM is DDR2 667MHz overclocked to 780MHz and CPU-Z says my RAM is 195MHz. I have yet to figure out why or how this is, I have spoken with a few very knowledgeable people and I have skimmed a few of my hardware books with no promising answer. The best I can say, is it's platform specific.

 

[detoam]

Thank You. very informative. I am so far behind on all of this I don't think i will ever catch up.

 

[Matthew DeCarlo]

You're welcome, and nobody is ever "caught up" per-say. It's impossible when things change every second of the minute and every minute of the hour.

I can't understand myself why it is that it's reported at 1/4 the marketed frequency sometimes, and yet more commonly it's reported at 1/2.

That said, within the next 24 hours I am sure someone will post in here and offer their spin on things, and project it as something that is fact, when it's probably not fact nor correct. Make sure you cross-check things for yourself so you don't wind up more confused.