P4P800 doesn't have 400MHz DDR option?

[ryandinan]

Hello,

I just got my P4P800 yesterday, paired with my P4 2.4B and Corsair XMS3200. For some reason, I don't have a 400MHz DDR frequency option - Just 266, 333 and Auto. The manual however, shows a 400MHz option in there as well.
If I leave it set to Auto, it uses 333MHz - so that's as high as I can go.
Now, I haven't had time to get new BIOS yet, but 400MHz DDR support was advertized as a feature - so I would think it would be in the shipping BIOS.

Or... Do the DDR frequencies available to you depend on the type of processor (400, 533, and 800 fsb)? There's got to be a way to run my memory at 400MHz?!


Thanks for the help!

-Ryan

[Chuck232]

Yes, the NBstrap defines the ratios you'll have. For example.

A 533MHZ FSB proc would have a 1:1 and a 4:5 ratio, giving 266MHz and 333MHz. At 800MHz FSB, you get the 3:2, 5:4 and 1:1 ratio, giving you 266MHz, 320MHz and 400MHz RAM speeds.

[natgun]

you must have an 800fsb processor to run dual-channel ddr400

[ryandinan]

Originally posted by Chuck232
Yes, the NBstrap defines the ratios you'll have. For example.

A 533MHZ FSB proc would have a 1:1 and a 4:5 ratio, giving 266MHz and 333MHz. At 800MHz FSB, you get the 3:2, 5:4 and 1:1 ratio, giving you 266MHz, 320MHz and 400MHz RAM speeds.

I'm a little confused...NBstrap? What is that?
And I'm a bit puzzeled how you got the above ratios as well...I understand what they mean - but I just don't understand why they would be limited to what you have. Why couldn't there be a 4:6 ratio to allow 400MHz DDR on a 533MHz fsb? My old SiS 645DX had it, as well as the other ratios you listed.

thanks!

-Ryan

[ryandinan]

Here's one more question...

The P4P800 doesn't list ratios - just frequencies. So if I end up raising my FSB to say 150 or 166MHz, will the DDR frequency stay locked to 333MHz?

Thanks!

[Chuck232]

Once you get to 200MHz FSB, you'll have the 400MHZ option unlocked. I dunno why you don't have the 4:6 ratio available, but guess it's just locked in the BIOS.

The frequency will always say 266, 333 (or 320) and 400. They won't say anything else, but you know that to be 1:1 and 4:5 in 533 NBstrap (which is the setting for your CPU, 533MHZ) and 3:2, 5:4, and 1:1 in 800 NBstrap.

[ryandinan]

Gottcha - so If I ran at 150MHz fsb, the memory will still say "333MHz", but it'll really be running at 375MHz - and 166MHz fsb will give me 415MHz DDR.

I know my chip will do 2.7GHz (150 fsb) no sweat with a voltage of 1.6, but I'm not sure I want to push it much higher, as my last northwood died of SNDS - but then again, I ran that at 1.85v for a year...

Thanks again!

-Ryan

[Chuck232]

Originally posted by ryandinan
Gottcha - so If I ran at 150MHz fsb, the memory will still say "333MHz", but it'll really be running at 375MHz - and 166MHz fsb will give me 415MHz DDR.

I know my chip will do 2.7GHz (150 fsb) no sweat with a voltage of 1.6, but I'm not sure I want to push it much higher, as my last northwood died of SNDS - but then again, I ran that at 1.85v for a year...

Thanks again!

-Ryan

Yes, the BIOS doesn't reflect the change in FSB in terms of the ratios, but it's working.

And 1.85V Yikes!

[ryandinan]

Originally posted by Chuck232

And 1.85V Yikes!

Yeah
The processor didn't like it very much either...
What's funny is that the chip still works for 99% of the stuff I throw at it. The only thing that seemed to get damaged was it's ability to process certain calls for Directshow applications such as WindowsMedia 9 and certain directshow DVD software. I can run 3d apps/games on it all day, and it doesn't flinch..


-Ryan

[Chuck232]

Originally posted by ryandinan
Yeah
The processor didn't like it very much either...
What's funny is that the chip still works for 99% of the stuff I throw at it. The only thing that seemed to get damaged was it's ability to process certain calls for Directshow applications such as WindowsMedia 9 and certain directshow DVD software. I can run 3d apps/games on it all day, and it doesn't flinch..


-Ryan

Weird, well because of that, are you sure it's the CPU's problem?

[ryandinan]

Yes - I swapped out processors, and I can play that kind of stuff just fine. Plus I was getting some cpu errors reorted in the event viewer.

-Ryan