Dewayne Thomas wrote:
> I'm upgrading my system and really don't understand the relationship
> of the front side bus speed and the memory speed. I'm looking at the
> P5L-NM 1394 which list the FSB speed at 1066/800/533 MHz and the
> memory speed at 667/533/400 MHz. Is the FSB speed set according to the
> CPU and if the CPU is not locked can I crank it up to the max? Also is
> the mem speed have to be some ratio to the FSB speed?
>
> Mabe some one can answer this or point me to a reference that covers
> it. The books I have looked at so talk to the FSB speed but really
> don't say if it can be changed or what should the mem speed be in
> relation to a FSB speed.
>
> Appreciate any comments on the subject.
>
> Dewayne
>
On the outside of the processor, there is a clock signal fed to it.
The clock signal is used for two purposes. It sets the speed of the
FSB. And that clock is multiplied up, to become the core clock for
the processor.
Say you had a FSB1066 processor. The input clock to the processor
is 266MHz. Intel busses are quad pumped, meaning the input clock is
multiplied by 4, to get the FSB transfer rate of 1066 million
transfers per second. Now, say the core multiplier is 9x.
266 x 9 = 2400MHz. That would be a processor with a 2.4GHz core.
The multiplier is constrained or "locked", to prevent the multiplier
from being raised any higher. (The X6800 would be an exception, and
for some of the fastest processors, Intel leaves the multiplier unlocked.
But for the stuff you can afford to buy, the multiplier is limited, as
in the example of 9x.)
To raise the core clock higher, means increasing the input clock to the
processor (since we cannot change the multiplier in a useful way). That
is how people overclock. But doing so, causes the FSB to go up too.
Which is why people prize motherboard that can handle extremely high
FSB values. Some of the "value" motherboards, handle high FSB values poorly.
We haven't talked about memory at all yet. The memory clock is set
by means of a ratio to the main input clock. You can select a memory
setting, to keep the memory clock within the stated limits of the
memory you bought. If you plan on increasing the input clock (because
you want to overclock), you use a lower memory setting. The combination
of a lower memory setting, plus a higher clock, results in the memory
clock still meeting its spec. So basically, you dial down the memory,
to compensate for dialing up the clock.
I'm assuming the model you are interested in, is the P5L-VM 1394. Integrated
graphics chips are not always the best overclockers, and the 945G is
an older generation chip. Also, at least some of the Asus microATX
motherboards, lack useful BIOS settings, if you are interested in
overclocking, or even adjusting things for that matter. Always
download the manual first, and read the BIOS section thoroughly, to
see whether the CPU clock, memory ratios, memory timings, Vcore, Vdimm
and the like, can be adjusted. Vdimm is important, because for at least
some of the fancy memory out there, it doesn't work well until you
turn up the Vdimm voltage a bit.
http://www.asus.com.tw/products4.asp...3&l2=11&l3=194
There are very few posts in the Asus forum for P5L-VM 1394. Which means
not a lot of people are using it.
http://vip.asus.com/forum/topic.aspx...Language=en-us
And there is one report of a dead NIC when the motherboard was received, here.
But otherwise, the reports are pretty positive, compared to some other motherboards.
If you are not overclocking, maybe this will do fine. If the NIC dies, you can
always slap a cheap Ethernet card or wireless card, into the machine.
http://www.newegg.com/Product/Produc...82E16813131046
Paul
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