Higher or lower Multipler,FSB whats the best for a stable overclock ?

[Paul Mathews]

Just getting a mobile 2500 and want to overclock it to atleast a Amd
PR Rating of 4000 , 2.5ghz.

And just want to know the best most stable way of doing it.

Thanks.

 

[Ben Pope]

Just getting a mobile 2500 and want to overclock it to atleast a Amd
PR Rating of 4000 , 2.5ghz.

And just want to know the best most stable way of doing it.

The common way is to up the FSB as high as possible with RAM in synch,
whilst using a low multiplier. High as possible meaning, as high as it will
go stable - using memtest86+ and prime95 torture test to check stability.
Then using Prime95 to get the multiplier as high as you can, whilst
remaining stable.

Then there's that area of crossover where you might be able to hit the next
multiplier by reducing the FSB a tad, which may, or may not be better for
you (depending on the balance of memory bandwidth to number crunching
requirements). It's also pretty useful to use MBM5 or some other decent
monitoring program to check your cpu core (diode) temps under load (prime95
torture test) if you up the voltage to achieve your overclock (which it
sounds like you'll need to, given where you want to end up).

If you want to take your FSB high, like above 200MHz, then you'll need an
nForce2 to lock your PCI and AGP buses. (unless there are any boards with a
7 divider?).

Your question really depends on your hardware, but the generic response is:
FSB as fast as you can, stable.

Ben

 

[BigBadger]

Just getting a mobile 2500 and want to overclock it to atleast a Amd
PR Rating of 4000 , 2.5ghz.

And just want to know the best most stable way of doing it.

Thanks.

For best performance run memory in synch with FSB as high as it will go
stable.
If you want to hit 2.5GHz you will need good air or good water cooling and
a good overclocking motherboard...I have good results with a SP97 cooler
and an NF7-S board running an XP2500 Mobile at 2650MHz....but I tried
several cpu's before I got ane this good.

 

[Vedran Parac]

correct me if I'm wrong, but in my opinion the following might help you:

the limiting components for high FSB are RAM and northbridge (providing that
PCI&AGP are locked, or around default values, and that RAM and FSB are in
sync).

The CPU isnt stressed by high FSB value but rather with multiplier X FSB
resulting frequency,

so the answer would be:

0. Set a low CPU multiplier, so that it is working at, for example 1.5GHz,
so you can be sure it's not the one that is generating errors, be sure it's
not overclocked.

1. raise FSB: RAM frequency ratio, so RAM is NOT woring in sync with FSB,
but on SLOWER frequecy.

2. raise FSB to the maximum stable frequecy northbridge will go. Now you've
got the top frequency your northbridge will go.

3. Now, get RAM and FSB in sync, and if it's not working error free, your
RAM is the limiting factor. Either get a better one, or lower your FSB
frequency. Don't just raise FSB:RAM ratio to get your RAM working slower,
you've achieved nothing if FSB is working slower than your RAM, CPU can only
access RAM as fast as RAM will let it.

4. Now, you've got RAM and FSB as high as they will work together, so you
need to find a maximum frequency your CPU will go.

To do so, get you FSB and RAM to their default, positively error-free
frequencies, and raise CPU multiplier until you find a resulting maximum
FSBxMultiplier frequency that your CPU will work on. You will get higher by
raising Vcore, but be aware of the heating issues, and your warranty void
conditions, don't blame anyone for your decisions

--
appendix:
test stability with prime95, burncpu, docmem, memtest
at least a few hours of prime95 is recommended, I've had errors after up to
8 hours of testing, but if the system is quite unstable, it will generate an
error in a few minutes of prime 95's torture test . Sufficent to let you
know you've pushed it too far in current setup.

disclaimer:
You are responsible for your own actions. This information is given as it
is, with no warranty of any kind, either expressed or implied. Warranty will
be void or valid under conditions specified by responsible hardware
providers. This information is for educational purposes only.