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A question about i850E

I hear they are supposed to be released on May 6'th, so probably mid may or so. Running a i850e with a 100mhz fsb P4 would be just like running an AMD Duron on a 133mhz KT266a, it automaticly switches to 100mhz fsb. Your best bet is to buy one of the i850e boards, and get a 100mhz fsb P4 to hold you over till prices on the 133mhz fsb P4's drop.
 
Here's the way it'll work. The RDRAM clock is based on the front side bus times a multiplier. Most boards have 3x and 4x multipliers. So if you do the math, at 533fsb (133MHz QDR), you can get 133X3 (399MHz, AKA PC800), or 133X4 (533MHz, AKA PC1066). However keep in mind that at 400fsb (100MHz QDR), you won't be able to run memory at PC1066 speeds 400fsb CPU (100X3 =300MHz AKA PC600, and 100X4 = 400MHz AKA PC800), you understand what I mean?
 
Are you sure it will run? i thought the 533 P4's were going to be a different die size. would that mean that it is the same pin out as the older northwoods? will it run the same voltage?

i'm not sure that it is such a clear answer.
 
they'll keep the same pinout, its just a stepping change. AFAIK no one has ever changed their socket with a stepping change.
 
Q]However keep in mind that at 400fsb (100MHz QDR), you won't be able to run memory at PC1066 speeds 400fsb CPU (100X3 =300MHz AKA PC600, and 100X4 = 400MHz AKA PC800), you understand what I mean? [/i] >>



Unless you use a chip such as the 1.6 or 1.8 at 133. Correct?

Not knowing much about memory, this may be a stupid question, but
Would it ever be possible for Rambus to run asynchronously to the chips fsb?

 


<< unless you use a chip such as the 1.6 or 1.8 at 133. Correct? >>

It really doesn't matter weather the chip is an offical 533fsb part or a 400fsb part oced to 533 (like many are doing with the 1.6A).

<< Not knowing much about memory, this may be a stupid question, but
Would it ever be possible for Rambus to run asynchronously to the chips fsb? >>

Well actually, Rambus is always running asynchorusly to the front side bus (in a 533fsb+PC1066 configuration, the fsb clock is 133MHz QDR and the Memory is 533MHz DDR). You have to remember that while the effective frequencies are 533MHz and 1066MHz, the actual frequency is lower because in QDR you are getting 4 bits per clock cycle instead of one bit, and with DDR you're getting 2 bit's you know?
 
If you lay it all out on the table, there isn't any FSB higher than 133mhz unless you overclock, these numbers from DDR and QDR are a smoke and mirrors type deal. DDR doubles data rate so you get an effective, but not true 266mhz FSB. QDR quadruples data rate so you get 533. RDRam(QDR) runs dual channel, so 533x2=1066, hence the PC1066 name.
 
So all I need to do is set the fsb to 100MHz and use PC800 (4*100) with the P4.

Also, will the change in fsb affect PCI, AGP,.... ???
And finally, any recommandation about RDRam supplier (Samsung, ......???) would be great.
 
Samsung

8 Device 256MB PC800 if NOT planning on overclocking
16 Device 256MB PC800 if planning on overclocking

8 Device is higer density.. slightly less latency, but harder to overclock
16 Device is the opposite.

If getting 128, 8 becomes 4 and 16 becomes 8.


As for the PCI/AGP spec. Boards like the Abit TH7 II have a setting which allows you to fix the AGP/PCI bus speeds so they never change regardless of the FSB you set it at. (Someone on HARD OCP(?) verified that it does as advertised with an Oscilliscope).

For most other boards, as far as I know, if you run at 533 FSB / 400 FSB there is a ratio in the bios to have your PCI/AGP run in spec. Anything in between will alter the PCI/AGP speeds.
 


<< One last question comes to my mind, will PC800 (400MHz) and PC1066 (533MHz) fit in the same RIMM? >>


yes.
 


<< << One last question comes to my mind, will PC800 (400MHz) and PC1066 (533MHz) fit in the same RIMM? >>


yes. >>



I don't believe so; aren't PC1066 RIMMs 32-bit? You only have to install 1 of them, rather than 2.
 


<< I don't believe so; aren't PC1066 RIMMs 32-bit? You only have to install 1 of them, rather than 2. >>

Not necessarily, though 32-bit bit PC1066 RIMMs will be available, and they'll be called RIMM4200. 32-bit PC800 RIMMs will be available as RIMM3200.
 
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