P4 800. What is the memory ACTUALLY running at?

I have been into AMD for the past few years, and I want to build a new machine for the house. Want to get a quick Intel just so I am not a fanboy anymore.

But what I want to know is what is the memory actually run at?

I know with AMD it is 2x the FSB, so 200 is 400, you need DDR400 (3000).

But with Intel its 200x4, and there is no way you are going to get DDR400 to run at 800 so whats the deal? This is the only thing holding me back from my purchase and I can't find any info anywhere.

Thanks

Bry

The memory is the same, the P4's have a quad pumped bus where the AMD's have a dual. So basically the new "C" CPU's (800 FSB) can handle twice the bandwidth of the AMD's. It is still DDR and the faster rated ram, the better (DDR 400 is 3200 BTW).
You really need a minimum of GOOD 3200 Ram. When you start to OC (if you choose to, but then if you didn't, you wouldn't be here ) there are many ram dividers you can use. 1:1 will run the memory exactly as you set the FSB so, if you set the FSB to 220, the mem will run at 220 or DDR 440. There will be a point where you need to use the 5:4 divider (FSB x .8). Say your CPU will run at 250FSB, your ram probably will not run at that speed so you set the 5:4 and now your ram is running at (250 x .8 = 200) 200 or DDR 400. If your CPU is really smokin, and you can get to 300 FSB (maybe with a 2.4C) then you would employ the 3:2 divider (FSB x .666) so 300 x .666 = 200 or DDR 400 again. It can be confusing but the ram for P4's runs in the same way as for AMD only the P4's use different dividers to keep the ram at a speed it will run at.

Intel chips run at 100, 133 and 200 FSB.

at 200 FSB the main ratio used is 1:1, so the memory runs at 200 FSB. Because DDR is double-pumped it will run at 400.

OK I think I get it.

Here is the thing though.

When you start overclocking and changing the dividers, everything is running asynchronous. Is there a big performance hit when you start doing that?

brywalker said:

OK I think I get it.

Here is the thing though.

When you start overclocking and changing the dividers, everything is running asynchronous. Is there a big performance hit when you start doing that?

Click to expand...

Not like there is with AMD. I can run my mem at 1:1 at 250FSB for DDR 500 with 7-3-3-2.5 timings. My sandra mem scores are just over 6K. Now, my everyday settings are 277FSB with the 5:4 so my ram is running at 222 or DDR 444 with 5-2-3-2 timings and my Sandra mem scores are a bit BETTER than running the mem at 250 1:1. The reason why is that the P4's LOVE the high FSB and can use all the bandwidth where the AMD's can not.

brywalker said:

OK I think I get it.

Here is the thing though.

When you start overclocking and changing the dividers, everything is running asynchronous. Is there a big performance hit when you start doing that?

Click to expand...

not realy...

I've done some crazy reading on the comparisons of running a 1/1 ratio vs 4/5 and 3/2

I've found that when you run at 4/5 you do loose about 5% performance, but this can be so small that you may never notice it.
when you run the mem at the slower ratio of 3/2, you will find that you may loose about 8-10% performance as compared to a 1/1 ratio at the same FSB.

the good news is that your OCed cpu will still get faster...by alot.
the reason you only get a small loss is that your cpu will be running a high FSB, and that helps to make up some bandwith.

I don't know what 800bus cpu your thinking of getting.....
may I sugjest the 2.6c
a good springdale (865)or canterwood(875) mobo and pc3500 will give you great performance and good memory timmings.

remember, you'll need two sticks of memory for the dual DDR mobos.

mica