PC3200 DDR 400 MEMORY RUNNING @200Mhz

[3008n1]

The BIOS says the ram is running at 400 Mhz. BUT, three benchmark programs all say it is running at 200 Mhz. Which do I believe? How can I prove it? The MOBO is ASUS P4P800-E. I am doing NO fancy over clocking, just wanted a rock solid system.

I have switched banks and sets of ram with no change in the 200 Mhz.

Any ideas.


Tom

 

[stuuked]

pc3200 ddr 400 is usually built to run at 200mhz by default but is effective at 400, which means to get the full effect of that ram, you will need to overclock it. you should read some documentation from the makers of the ram before you do it, you dont want to burn it out.

 

[shadesdude]

It depends on what kind of processor you are running but Intel's use a bus multiplier of 4 and AMD's have a bus multiplier of 2. This makes me tink you have a AMD but the BIOS will show you the mulitiplier frquency and the software will give you the base frquency. If you have more questions joanthan_tubb@yahoo.com.

 

[shadesdude]

It depends on what kind of processor you are running but Intel's use a bus multiplier of 4 and AMD's have a bus multiplier of 2. This makes me tink you have a AMD but the BIOS will show you the mulitiplier frquency and the software will give you the base frquency. If you have more questions jonathan_tubb@yahoo.com.

 

[shadesdude]

oops the second post has the correct e-mail

 

[3008n1]

Thanks for your input. I was afraid I was "taken" when I bought this setup.

It sounds like it could be an honest mistake--or not even that. Just hard to understand technology.



Tom

 

[cdogg]

The FSB should be running at 200MHz for newer Intel P4 CPU's. The memory bus usually runs in synch, so in this case, it should also be set to 200MHz.

Because DDR SDRAM sends twice as much data per cycle as regular SDRAM, PC3200 is given the rating of 400MHz. So internally, it's running at that speed. The 200MHz is the "true" speed, and the 400Mhz is the theoretical.

Here's where it can get confusing, however...

If you have a P4 that supports the 800MHz FSB (200MHz x 4), then the BIOS is correctly set. However to get the most out of your setup, you need to run PC3200 in dual channel, which requires two identical DIMM modules. See your manual or visit Intel's site for more info...

~cdogg
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884

 

[Sheco]

Imagine a square wave... or look at the first picture here:

http://en.wikipedia.org/wiki/Square_wave

Here is some ASCII art:
  _   _   _   _
_| |_| |_| |_| |_

Now imagine that this waveform is triggering some action inside your computer at 200 Mhz.

The action that is triggered could fire every time the wave goes high... or it could be triggered on the edge transitions... so once on by the rising edge and a second time on the falling edge... so that you get a "double" rate... now your 200 MHz waves triggers 400,000,000 times per second.

 

[cdogg]

Sheco,
That's a good way to picture it. Another way is using the "traffic lane" analogy, which also helps demostrate why 200MHz "double-pumped" would not be as effective as true 400MHz speed.

Imagine a 2-lane highway that has just been increased to 4 lanes. Twice as much traffic can pass at any one time. The key here is the speed limit. Although you have expanded your highway, you are still only able to reach the destination in the same amount of time as before. As with the memory bus, data is not constantly flowing at the max bandwidth rate, meaning that all 4 lanes aren't being used to their full potential at all times.

This is less an issue with memory, as it is with the FSB.

~cdogg
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884

 

[3008n1]

Hello.

Mu MOBO is A P4P800-e ASUS. The FSB is 800Mhz.Dual Channel technology.
Did I gain by purchasing 400Mhz Memory, or is that the standard? WOuld 200 be as good?
I do understand both of your explanations. But he told me to get the 400Mhz because if would be faster (and more $).
I have 2 banks of two. Each has a 512Mb. module or ram-pc3200. (4 total for about 2048Gb ram)
Would 400Mhz ram be much faster, since it is "wider" then previous busses. The processor is the Presscott.

I played with overclosking, but the ram does NOT run at 400Mhz. This is so confusing to me.

Thanks guys for your time,

Tom