nForce3: Relationship of the Multi's with Ram @ 166Mhz

[MrIcee]

It's been quite an adventure the last day and a half finally having a play and success with the A64 aboard the Shuttle AN50R. I thank the early adopters out there for all their excellent input here on the forums when I yet did not have an A64 system to develop.

One thing that is quite different running asynch on these nForce3 150 boards is the relationship of the multiplier to the actual FSB/Ram divider compared to an Intel 865/875 board.

On the Intel boards of course you are stuck with one multiplier....and memory scales relative to FSB at the 5:4 ratio.

Not so with nForce 3. I found this quite interesting in my bandwidth assessments because between 6x and 6.5x the ratio changed and the performance, tho better because of the higher FSB at 6x could have been substantially better if the ram was relative to the FSB consistently, but it IS NOT.

Here is a rundown of the multipliers and the FSB/Mem settings as they relate to each multiplier selection when the bios is set to 200FSB/166Mem Asynchcronous mode:

Multiplier

10x - 200/166.67
9.5x - 200/158.33
9.0x - 200/163.64
8.5x - 200/154.55
8.0x - 200/160.00
7.5x - 200/166.67
7.0x - 200/155.56
6.5x - 200/162.50
6.0x - 200/150.00
5.5x - 200/157.14
5.0x - 200/166.67
4.5x - 200/150.00
4.0x - 200/160.00

As can be discerned from this chart, the optimum multipliers for developing maximum bandwidth, particulary over 300Mhz FSB if you have the memory that can produce at these asynch speeds, are 10x, 9.0x,8.0x, 7.5x, 6.5x and 5.0x.

At 200/166.67...if you run 300Mhz FSB you're memory will be at 250Mhz, at 330Mhz it would be 275Mhz. This produces gobs of bandwidth on the A64 as witnessed by the 4141/4105 @ 1653Mhz I posted up on the A64 bandwidth thread.

Never the less, I have run at the less desirable 6x multi at 334Mhz FSB/250Mem(2x LDT) successfully in 3Dmark. With any luck and Prommy cooling I hope to utilize one of the more desirable multi's for 3Dmark benching.

Anyways, just thought these figures may be helpful to those running nForce 3 150 asynch.

Best Regards,

Randi

[Firelord-OCHW]

Sounds well confusing!!!

[STEvil]

lol.. fun 8-)

[Penti]

Well "5:4" on 3200+ should use memdivider CPU/12 in 2000MHz. So its really cpu frequency that it depends on. Not the multiplyer or FSB.

So it should be something like this
10x - 200/166.67 = 2000MHz - CPU/12 divider
9.5x - 200/158.33 = 1900MHz - CPU/12 divider
9.0x - 200/163.64 = 1800MHz - CPU/11 divider
8.5x - 200/154.55 = 1700MHz - CPU/11 divider
8.0x - 200/160.00 = 1600MHz - CPU/10 divider
7.5x - 200/166.67 = 1500MHz - CPU/9 divider
7.0x - 200/155.56 = 1400MHz - CPU/9 divider
6.5x - 200/162.50 = 1300MHz - CPU/8 divider
6.0x - 200/150.00 = 1200MHz - CPU/8 divider
5.5x - 200/157.14 = 1100MHz - CPU/7 divider
5.0x - 200/166.67 = 1000MHz - CPU/6 divider
4.5x - 200/150.00 = 900MHz - CPU/6 divider
4.0x - 200/160.00 = 800MHz - CPU/5 divider


Regards

[xxORBxx]

Man this confuses the hell outta me. I think i might need more explainin when i get mine here.

[QuadDamage]

MrIcee,

thanks for your input. Sounds pretty clear to me. I hope i will add some to this thread once i find some time and hook up a modded Prometeia unit and Gigabyte nForce3 150 mobo.