quick FSB question

[tipoo]

is there any advantage of having a fsb of 155x10 over 133x11.5? just to save you the math, they equal out to be the same.

 

[qcmadness]

is there any advantage of having a fsb of 155x10 over 133x11.5? just to save you the math, they equal out to be the same.

Depends on the chipset.

155x10 may be better for faster FSB.

 

[tipoo]

is there any advantage of having a fsb of 155x10 over 133x11.5? just to save you the math, they equal out to be the same.

Depends on the chipset.


explain... :?

 

[YO_KID37]

is there any advantage of having a fsb of 155x10 over 133x11.5? just to save you the math, they equal out to be the same.

Depends on the chipset.


explain... :?

In FSB What's a Bigger Number??
155Mhz Or 133Mhz?
IF you see what I'm getting to Then you would understand why 155FSB(overall Computer speed) over 133FSB(Overall Computer Speed) The Multiplier 10 vs 11.5 Is stressing the CPU, Not the Entire Computer. So when comparing the 155 Will Stress The Entire Computer, but the Higher Multiplier will only Stress the CPU more. So what's better a Faster Computer Or a faster CPU??

 

[outlw6669]

The higher fsb will give your cpu and ram more bandwith.
This will make it faster @ the same cpu speed than just bumping up the multiplier.

 

[JMecc]

Wouldn't memory latency be lower with the 155FSB (since the processor can get data to operate with at a faster rate). I would think this helps processing of large datasets. What do you all think?

Jo

 

[darkstar782]

I'm going to assume he has an Athlon XP processor, just from the numbers....

It does depend on his chipset as anything other than an nForce 2 Ultra will be trying to run the AGP/PCI clocks waaay out of spec and it likely wont run at 155MHz.

166*9.5 for example would be close and run the AGP/PCI clocks in spec on a VIA KT600 or similar board...

Basically, yes 155MHz is your FSB and faster there is better, although it doesnt make the CPU itself faster, but to know if its a good idea we need to know the full system specs.

 

[Pippero]

If he has an Athlon XP processor, then having a faster FSB is going to help a lot.
The (slow) FSB has always been the main bottleneck of the K7 architecture.
Having a faster FSB does not necessarily mean having lower memory latency though, this only if the FSB and memory are running in synch (that doesn't happen for example with a 166MHz FSB and 133 (or even 200MHz) DDR memory)

 

[tipoo]

I'm going to assume he has an Athlon XP processor, just from the numbers....

It does depend on his chipset as anything other than an nForce 2 Ultra will be trying to run the AGP/PCI clocks waaay out of spec and it likely wont run at 155MHz.

166*9.5 for example would be close and run the AGP/PCI clocks in spec on a VIA KT600 or similar board...

Basically, yes 155MHz is your FSB and faster there is better, although it doesnt make the CPU itself faster, but to know if its a good idea we need to know the full system specs.

your right, its an athlon xp 1800+ thoroughbred, on a kt4v mainboad (kt400 chip) and 512mb pc 2700 Ram (i dont know exactly how all the timing thingys work, but the cas latency is 2.5). its an AGP board (obviously.)

 

[JMecc]

How did you change the FSB & Multiplier? Did you have to use the "wire trick"? I have options to change these on my A7N8X-E Dx but it will not post unless the specs are the natural ones for my 2800+.

Jo

 

[tipoo]

How did you change the FSB & Multiplier? Did you have to use the "wire trick"? I have options to change these on my A7N8X-E Dx but it will not post unless the specs are the natural ones for my 2800+.

Jo

i just go into the BIOS by pressing delete at startup. then i go into frequency and voltage control, byt your BIOS are probly different than mine. maybe your board dosnt support changing the multiplier.

 

[darkstar782]

With a KT400 you shouldn't be able to unlock the multiplier without a wire mod, unless you have an XP-M (mobile) which come unlocked. You can tell by looking at the L3 bridges but that involves taking the cooler off and getting a decent amount of light inside the case....

With decent cooling you can run T'bred Athlon XPs at 1.95v for extended periods without electron migration killing them, I had a crappy water loop on my old 2600 (2.083GHz, 166FSB stock) running at 2.5GHz with a 200 FSB like this for a looong time.

Eventually the motherboard caps started leaking, as motherboards of that era are prone to do, but the CPU was still fine, and is currently running in another motherboard in my little brothers PC at my parents house.

A higher FSB will be good for you, but the KT400 does NOT support PCI/AGP locking, so you basically have 4 FSB numbers that will keep the system stable, 100 (waaay slower than stock, useless), 133 (stock), 166 (decent overclock, may need to drop the multiplier a little), 200 (massive overclock unless you drop the multipler, 200x8 for 1600 CPU would be a nice initial overclock. The RAM should handle it if set to CL3 loosen the other timings as much as you can)

As for the wire trick not working for JMecc, the multipliers the BIOS asks for are often not the ones the chip will aim for. This is because when multipliers started getting higher than a certain generation of mobos could handle, AMD and Intel started making a requested 12x post at 20x, and similar. This means that when you set the multiplier on your 2800 from its default (which varies, there are threee different 2800s, 1 Tbred and 2 Barton) up by 0.5, from say, 12.5x to 13x, it may have tried to jump to 24x or something silly.

What you should do is map the actual multipliers. Set the FSB to 100 (to enable it to post at the widest possible range of multis) and starting from the lowest BIOS option, record what actual multiplier each setting gives you.

Then you can set the FSB to what you like and overclock by multiplier

 

[tipoo]

thanks for all the input!

i put the fsb as 166 and the multiplier at 10 right now. i also put the CL at 3, like you said. everything seems to be stable right now, but i dont see any improvements in performance just yet... ill have to run some benchmarks for that. are there any other RAM timings i should change?
and also, are there any system stability testing programs i should use?
P.S. i dont know about any wire trick, i just seem to be able to change things around from the BIOS.

 

[darkstar782]

You wont need CL3 for 166FSB, try 200FSB and x8 or x8.5, you know you want to

Worse case scenario is that it wont boot, in which case pop the CMOS battery out, pull the plug, wait a few secs and put it back, and it will work fine.

Failing that, you can reset the CMOS via jumper but I always find them too fiddly.

If the system crashes or seems unstable, you may need a touch more voltage on the CPU, stock should be 1.6v or 1.65v on that CPU, 1.7v should be fine even with low end cooling.... keep an eye on the temps tho.

 

[tipoo]

You wont need CL3 for 166FSB, try 200FSB and x8 or x8.5, you know you want to

Worse case scenario is that it wont boot, in which case pop the CMOS battery out, pull the plug, wait a few secs and put it back, and it will work fine.

Failing that, you can reset the CMOS via jumper but I always find them too fiddly.

If the system crashes or seems unstable, you may need a touch more voltage on the CPU, stock should be 1.6v or 1.65v on that CPU, 1.7v should be fine even with low end cooling.... keep an eye on the temps tho.

wouldnt a 1:1 ratio with the RAM be better?

 

[darkstar782]

With the FSB@ 166 the RAM should run @166 CL2.5, this is what it is designed for as PC2700 RAM.

With the FSB@ 200, try running the ram @200 CL3, the looser timings should compensate for the extra speed. 2.7v on the Ram is a good idea too, and will be completely safe (alot of boards default to 2.6v for DDR1, rather than the 2.5v spec. 2.7v is nothing.)

That's 1:1 @ 200MHz....

Download WinRar 3.6 or later, and run the benchmark in the menu, this is very RAM sensitive and you'll notice much nicer results with 200MHz 1:1 than with 133MHz 1:1

Oh I loved overclocking Athlon XPs, so much more fun than current CPUs imho....

 

[BoomBatz]

If you are fiddling around with FSB speeds in the 133 or 155 range ...... does it really matter????? The performance is going to be absolutely horrible either way. Thats like asking ... hey man if you wore forced to sit there and watch, which amount of time will go buy faster, a) watching 10 lbs of uranium 328 decay (the half-life of uranium328 = 6000 years) completely, or sitting their and watching the entire coast of california fall into the ocean (about 2,000 years).

I mean it is really a silly question, that was probably asked by the same doof that rides around @ 40mph in the fast lane.

 

[darkstar782]

If you are fiddling around with FSB speeds in the 133 or 155 range ...... does it really matter????? The performance is going to be absolutely horrible either way. Thats like asking ... hey man if you wore forced to sit there and watch, which amount of time will go buy faster, a) watching 10 lbs of uranium 328 decay (the half-life of uranium328 = 6000 years) completely, or sitting their and watching the entire coast of california fall into the ocean (about 2,000 years).

I mean it is really a silly question, that was probably asked by the same doof that rides around @ 40mph in the fast lane.

Riiight....

Some people don't want to or can't just throw money at their PCs. An Athlon XP can still be a perfectly adequate gaming machine, with a reasonable GPU, and overclocking on them is a useful learning tool - you wont wreck a $1000 CPU.

He has already gone from 133MHz FSB to 166MHz, a 25% increase in bus speed and memory bandwidth, which WILL have made a difference to CPU performance in games.

There really is no need for the attitude.

 

[tipoo]

the comp wouldnt boot up a 8x200. i even knocked the voltages up...are there any more RAM timings i should change? i realy want to make this work, lol. and thanks for all the help so far, darkstar and everyone else.

and bty, i totaly agree. athlon xps are the funnest to overclock. i helped my friend overclock his core 2 duo, and that was nothing.

 

[darkstar782]

Try 8x100, is 8 actually 8 or is it going to something higher when you request 8?

Some AthlonXP/motherboard combinations do, its very annoying!

Does the motherboard allow you to set the RAM frequency independently? If so set the RAM to 166MHz, and the CPU to 200x8, just to see if it works. If it does we know it is the RAM holding you back from 200.

 

[darkstar782]

Opps, I forgot, the kt400 doesn't support 200MHz FSB, it is just a refresh of the kt333, you need a kt600 board for 200MHz FSB.

As such it wouldnt boot because the AGP/PCI clocks would have been way out of synch, you need to slowly raise the FSB by about 5MHz at a time and see how far it will go and stay stable. Unfortunately the APG/PCI clocks probably wont go far....

After you hit the max stable FSB with that, you need to slowly up the multiplier