Asrock 939 Dual SATA II Bios

[Phil Nicholls]

I've just spent the last two hours or so trying to get clairification
of some of the settings in my AMI bios.

I have an Asrock 939 Dual Sata II mb, and Amd 64 3500+ (Venice) CPU
and 1Gig of Corsair Value Select RAM (2 512MB set up as dual channel)

Can someone explain to me what "CPU-NB Link" is all about, as well as
SB-NB link and other associated settings. What are they and what do
they do and what are the optimal settings?

 

[Paul]

I've just spent the last two hours or so trying to get clairification
of some of the settings in my AMI bios.

I have an Asrock 939 Dual Sata II mb, and Amd 64 3500+ (Venice) CPU
and 1Gig of Corsair Value Select RAM (2 512MB set up as dual channel)

Can someone explain to me what "CPU-NB Link" is all about, as well as
SB-NB link and other associated settings. What are they and what do
they do and what are the optimal settings?

In the Athlon64 world, the external data busses use a standard
called HyperTransport. The width of the bus is variable, and
some BIOS allow some of the bits in the bus to be turned off.
So, the bus could be 2, 4, 8, 16... bits wide. A wider bus
can have a higher aggregate bandwidth. Artificially narrowing
down the bus, can reduce switching noise (i.e. if the chipset
was not stable and error free). Also, the clock is
programmable, and is multiplied from the basic clock fed
to the processor. On some interfaces, the nominal value
might be 200x5, where 200MHz is the normal clock signal
fed to the chips, and x5 is the multipler selected. If
the clock to the processor is increased (i.e. overclocking),
generally people turn down the multiplier, to stay within
the 1000MHz limit of the bus (or whatever it happens to be,
like 800MHz on some other systems).

Athlon64
Processor
| ^
| | HT bus
v |
PCI-E_Video-----PCI_Express_Tunnel
M1695
A.K.A Northbridge
| ^
| | HT bus
v |
AGP_video---------AGP Video plus
Southbridge Periphs
M1567

Generally, auto would be a good setting

Unless you are overclocking maybe. If you set the
clock to your CPU to 250MHz, instead of the normal 200MHz,
then you need a different multiplier. Since the bus in this
case is _probably_ rated for 1000MHz, the normal setting
would be 200x5. At 250MHz, we would want to change this
to 250x4. The "800MHz" setting in the BIOS is not a MHz
setting, as much as it is a "x4" multiplier setting. So,
to get the x4 multiplier, you'd select the 800MHz setting.
The resulting bus clock rate, is CPU_Clock * multiplier,
so the actual rate would be 250x4.

What I cannot tell you, is if "Auto" is smart enough to
choose a multiplier, based on the overclocked value of
the processor. That is why, if you set the clock to 250Mhz,
it might be safer to set the bus to "800MHz", just in
case Auto isn't clever enough to choose x4 multiplier
because the clock is so high.

As long as you are seeing no problems with the computer,
you can leave these settings cranked up (i.e. try to hit
the 1000MHz limit on the HT bus as best you can). The picture
above should give you some idea which slots and chips
are affected by which bus settings.

Paul

 

[Phil Nicholls]

In the Athlon64 world, the external data busses use a standard
called HyperTransport. The width of the bus is variable, and
some BIOS allow some of the bits in the bus to be turned off.
So, the bus could be 2, 4, 8, 16... bits wide. A wider bus
can have a higher aggregate bandwidth. Artificially narrowing
down the bus, can reduce switching noise (i.e. if the chipset
was not stable and error free). Also, the clock is
programmable, and is multiplied from the basic clock fed
to the processor. On some interfaces, the nominal value
might be 200x5, where 200MHz is the normal clock signal
fed to the chips, and x5 is the multipler selected. If
the clock to the processor is increased (i.e. overclocking),
generally people turn down the multiplier, to stay within
the 1000MHz limit of the bus (or whatever it happens to be,
like 800MHz on some other systems).

Athlon64
Processor
| ^
| | HT bus
v |
PCI-E_Video-----PCI_Express_Tunnel
M1695
A.K.A Northbridge
| ^
| | HT bus
v |
AGP_video---------AGP Video plus
Southbridge Periphs
M1567

Generally, auto would be a good setting

Unless you are overclocking maybe. If you set the
clock to your CPU to 250MHz, instead of the normal 200MHz,
then you need a different multiplier. Since the bus in this
case is _probably_ rated for 1000MHz, the normal setting
would be 200x5. At 250MHz, we would want to change this
to 250x4. The "800MHz" setting in the BIOS is not a MHz
setting, as much as it is a "x4" multiplier setting. So,
to get the x4 multiplier, you'd select the 800MHz setting.
The resulting bus clock rate, is CPU_Clock * multiplier,
so the actual rate would be 250x4.

What I cannot tell you, is if "Auto" is smart enough to
choose a multiplier, based on the overclocked value of
the processor. That is why, if you set the clock to 250Mhz,
it might be safer to set the bus to "800MHz", just in
case Auto isn't clever enough to choose x4 multiplier
because the clock is so high.

As long as you are seeing no problems with the computer,
you can leave these settings cranked up (i.e. try to hit
the 1000MHz limit on the HT bus as best you can). The picture
above should give you some idea which slots and chips
are affected by which bus settings.

Paul

Well, I just smacked myself on the head. I couldn't figure out what
NB and SB stood for. Northbridge/Southbridge. Duh.

SiSoft Sandra says my "auto" = 800Mhz. Since the chip is advertised
at 1000 I can step those up if I wish.

Thanks!

 

[UVP]

On Sat, 01 Jul 2006 15:22:55 -0400, (e-mail address removed) (Paul) wrote:
SiSoft Sandra says my "auto" = 800Mhz. Since the chip is advertised
at 1000 I can step those up if I wish.

Yes. I have the same mb and the auto settings are not optimal. If you are
not overclocking then set it to 1000mhz and NB/SB link width to 16bit. Also,
if you use auto for the ram it is probably set at 133mhz instead of 200mhz.
Bump that up to 200mhz manually.