cpu fsb ? 2

[drunkmestupid]

i've just received an Abit KT7-Raid mobo and an AMD Athlon 1000Mhz 200FSB cpu.

how can i "make sure" that the chip FSB is running at 200Mhz? CMOS only shows FSB settings up to 155Mhz.

now if you go to abit's website and check out the specifications, it says the board supports Athlons with 100/133 FSB.

from what i've been told, the board will run it at 200Mhz, but Abit supposedly lists the "actual" FSB not the "doubled" FSB. is this true?


i am a little confused on this, can anyone shed some light?


tia!

 

[cdogg]

There are many popular FSB speeds you'll see out there today:

- 200MHz
- 266MHz
- 400MHz
- 533MHz

In all 4 cases, the FSB is actually running at either 100MHz or 133MHz. AMD systems use a 2x multiplier while Intel systems are based on 4x. Instead of increasing the actual speed, they have found ways to cram more data per clock cycle. It's like widening a 2-lane road to 4 or 8 lanes but keeping the same speed limit.

With that said, you would want the FSB set at 100MHz for your system. Look for the 'clock multiplier' in the BIOS and make sure it matches Abit's and/or AMD's recommendations...


~cdogg

"The secret to creativity is knowing how to hide your sources."
- A. Einstein

 

[drunkmestupid]

cdogg that was awesome! thank you.

only one other question... you mentioned the multiplier (100Mhz x 2) and you said to look for the multiplier... now there is the "regular" clock multiplier for the CPU speed, but is there another for the FSB? i am not at home now so i can't immediately look... i think the online manual at abit has screenshots so i will go check that out when i get a chance.

again, thanks for your clear explanation.

 

[drunkmestupid]

ok... update. looking on the screenshot i mentioned (i remember it looking the same), here are the options as examples from the screenshot:

CPU Operating Speed 500
x-Multiplier Factor x5
x-CPU FSB/PCS Clock 100/33Mhz
x-CPU FSB Plus (Mhz) 0
x-Speed Error Hold Disabled


the description for CPU FSB Plus is this:

You can increase CPU FSB speed here. This means that you can increase the setting of the "CPU FSB/PCI Clock" item, and also independantly increase the CPU FSB speed. Twenty-nine options are available:0~28, with the default setting at 0. You can change this setting to increase CPU FSB speed. CPU FSB speed above the standard bus speed is supported, but not guaranteed due to the CPU specs.


now, to me this just gives me another 29Mhz to play with for overclocking. it does not seem like a multiplier.

so do i just set the CPU FSB/PCI Clock to 100/33Mhz and just assume it's being multiplied by 2 (since the board is made for the chip)?


on another note, my ram chips are PC133. there is a setting for "DRAM Clock." the options are "Host CLK" and "HCLK+PCICLK." i am assuming that if i have the CPU FSB/PCI Clock set to "100/33Mhz," and the DRAM Clock set to "Host CLK," then the memory would run at 100Mhz. likewise, if i have it set to "HCLK+PCICLK," then it will add 100 and 33 to run at 133Mhz. am i assuming correct?


thanks again in advance!

 

[cdogg]

To be honest, I'm not as well versed in configuration settings, but here's what I do know:

The CPU Operating Speed should reflect the speed of your CPU, of course. In your example, it appears to be running at half speed. The Multiplier Factor is what I was referring to before. Depending on the CPU, this is usually a reflection of the FSB. In other words, you would usually want a multiplier of 10 on a 100MHz FSB for an Athlon 1000MHz processor. Also, you rarely want to overclock the FSB/PCI Clock setting. Doing so can render your whole system unstable since you're increasing the PCI bus which can control items like your sound card or modem. DON'T make any changes just yet, however. Do some reading to make sure you need to change the mutiplier. I highly recommend you sift through documentation on AMD and Abit's websites. Here's a start for you:

http://www.pantherproducts.co.uk/Articles/Motherboard/BIOS/softmenuIII.shtml#CPU Operating Speed

http://www.8ballshardware.com/articles/duronoc/page4.cfm

~cdogg

"The secret to creativity is knowing how to hide your sources."
- A. Einstein

 

[CitrixEngineer]

No, you are not assuming correct on this point. The RAM will run at the speed of the FSB - this is how the processor stays in synch with it.

The 100 refers to the FSB speed, and the 33 refers to the speed of the PCI bus.

To your earlier points, the 0-28 Mhz increments are for the FSB, and will affect overall speed (at the potential cost of shortening your processors' life).

eg; If it was set to 1, then your FSB would effectively run at 101Mhz. you would then do the maths; 101 * 2 = 202. This is the effective FSB speed. Then 202 x 5 (multiplier) gives 1010 - the "new" speed of your processor. At the highest possible setting, therefore, your processor would be running at 1280Mhz, and the RAM at 128. You may see signs of instability at this level, such as system lockups, since the PCI and AGP buses will not be unaffected.

Your RAM will run at the same speed as the FSB, hence increasing the FSB is one of the most effective ways of increasing overall system speed.

No manufacturer in their right mind would support anyone doing this, but companies like ABit and MSI realised a while back that there's a whole army of people who buy motherboards on the basis of their overclockability, so provide a way of doing it - without a guarantee!

Note; Some of the newer KTxxx boards - namely the KT333 and 400 support 166 and 200Mhz FSB's respectively. CitrixEngineer@yahoo.co.uk

 

[drunkmestupid]

CitrixEngineer,

i think you hit exactly was i was looking for.

"If it was set to 1, then your FSB would effectively run at 101Mhz. you would then do the maths; 101 * 2 = 202. This is the effective FSB speed. Then 202 x 5 (multiplier) gives 1010 - the "new" speed of your processor."

the clock multiplier is 5. thus i can now see how it is running at 200Mhz to reach 1Ghz...


as far as the RAM goes... this now makes sense. i would need to have a chip with FSB 266Mhz in order to run those chips at 133Mhz. but what then is this setting for DRAM? the information i posted came straight from abit's documentation... what effect would setting "Host CLK" as compared to "HCLK+PCICLK" have?

 

[drunkmestupid]

well, when i got home i checked and it is as cdogg stated... the multiplier is at 10 (100Mhz FSB * 10 = 1000Mhz CPU).

so what then about the doubling of the FSB? this takes me back to my original standpoint of "how can i tell that it (FSB) is being doubled to equal 200Mhz?"

these chips are marketed as 200/266Mhz just as the intels are marketed as 400/533Mhz. i understand it is really only 100/133 multiplied, but how can i check?

call me skeptical, but i want to be able to "see" where/how the system is registering this multipier on the FSB.

 

[cdogg]

The FSB and the Memory Bus are two different beasts. The FSB connects the CPU to the chipset on the motherboard (Northbridge). From there, the chipset is connected to several different components: AGP, RAM, and the Southbridge chipset.

To see a diagram, click here:

http://www.duxcw.com/digest/Reviews/MBs/Epox/8kha/2.htm

One of the major points to understand is that the memory bus, system bus and CPU speed all run on separate multipliers of the actual FSB. In this case, the actual FSB is 100MHz. The system bus is the FSB x 2 = 200MHz. This is the speed that data flows from the CPU to the Northbridge. The memory bus should run on a multiplier of 2, making it 200MHz as well. This would be the speed from the Northbridge to RAM. We've already discussed the CPU speed.

I'm not sure if this is the answer you're looking for, but if you don't see a setting for the memory bus in your BIOS, I recommend using a benchmark utility like Sisoft Sandra and compare your scores to other systems. Of course, you should be able to find something in the Abit manual or on their website if you need concrete evidence!

Good Luck!


~cdogg

"The secret to creativity is knowing how to hide your sources."
- A. Einstein

 

[drunkmestupid]

"The memory bus should run on a multiplier of 2, making it 200MHz as well."

cdogg,

everything you said makes sense. regarding the quote from above, the memory bus would run on a multiplier of 2 (200Mhz) IF it were DDR, correct?

on this board, it supports PC100/PC133... so it would just run at whatever the FSB is (in this case, 100Mhz), right?

thanks for taking the time to respond.

 

[gargouille]

Hello dms:

Yours is a natural tendency, but I think you'll find that most overclockers approach it from a different angle. Their ng's are quite a revelation as to HOW and WHY the settings they adopt are used. (usually lowering core voltage)
But just to show how much oc'ing is an accepted practice, most of the newer BIOS' have "high performance" defaults...and altho you may find the machine is unstable with them...ratcheting them down some may smooth things out as well as speeding them up.
Beware, too, the bogus expert: I suckered into loading a so-called (also self-anointed) expert's BIOS settings on a machine I have. (aided by the fact that it was exactly the same motherboard/RAM/CPU.)
It wouldn't even boot!
So much for that expert's credibility.

 

[cdogg]

Drunkmestupid,

Yeah, it appears I overlooked the type of chipset that you have. You're exactly right. Without DDR SDRAM, the memory bus and RAM will only run at 100MHz or 133MHz depending on whether you use PC100 or PC133 respectively.

Just goes to show how the FSB and Memory bus aren't necessarily identical. Good point!


~cdogg

"The secret to creativity is knowing how to hide your sources."
- A. Einstein

 

[CitrixEngineer]

Of course - I mixed up the KT7 with the KG7 - a board I own, which IS DDR.

:~/

Hope I was not too misleading on this CitrixEngineer@yahoo.co.uk

 

[drunkmestupid]

hey guys,

thanks for the info... i don't mean to beat this to death but... hehehe

"the memory bus and RAM will only run at 100MHz or 133MHz depending on whether you use PC100 or PC133 respectively.

Just goes to show how the FSB and Memory bus aren't necessarily identical."

so does the setting in the BIOS i mentioned earlier allow me to run the memory at 133Mhz even thought the FSB is 100Mhz? so you don't have to scroll through, here is what i posted again:

"there is a setting for "DRAM Clock." the options are "Host CLK" and "HCLK+PCICLK." i am assuming that if i have the CPU FSB/PCI Clock set to "100/33Mhz," and the DRAM Clock set to "Host CLK," then the memory would run at 100Mhz. likewise, if i have it set to "HCLK+PCICLK," then it will add 100 and 33 to run at 133Mhz. am i assuming correct?"

now i know CitrixEngineer replied:

"No, you are not assuming correct on this point. The RAM will run at the speed of the FSB - this is how the processor stays in synch with it.

The 100 refers to the FSB speed, and the 33 refers to the speed of the PCI bus."

if this is true, then what are these settings?


tia!

 

[cdogg]

To be honest, I don't know the exact answer to your question, because this is an older motherboard. Newer ones that use DDR and RDRAM aren't necessarily "in synch" with the FSB.

For example, take the P4 Northwood 2.53GHz CPU. It has a 533MHz FSB (or more accurately, "system bus" since the FSB really runs at 133MHz). However, there are DDR motherboards that advertise 533MHz FSB compatibility, but with DDR 266. Well, the RAM is clearly running at 266MHz, but we know the FSB is still at 533MHz. So, they don't have to be in synch...

Newer motherboards usually have a separate setting for the memory bus and PCI bus, especially ones meant for overclocking (not Intel chipsets). That way, you can increase or decrease the FSB frequency without disturbing the rest of the components in your system. RAM should not be overclocked if it can be avoided.


~cdogg

"The secret to creativity is knowing how to hide your sources."
- A. Einstein