FSB vs. RAM & Processor

[BigBlue66]

Hey Gang,

I think I know the answer to the question I'm about to pose to you all, but would like verification.

First, the history. Motherboard that supports either 200Mhz or 266Mhz FSB. Athlon processor with 200Mhz FSB. Two sticks of PC100 and one stick of PC133.

When I installed the motherboard, I considered the bus speeds of my processor and most of my memory. So, I set the FSB jumper to 100Mhz.

Now, I find that I can swap out the two sticks of PC100 for two sticks of PC133, making PC133 all around.

Question: Should I or could I set the FSB jumper to 133Mhz, so that the memory would benefit? Seems I read somewhere that SDRAM runs at the motherboard's FSB. Right? I realize that the processor won't benefit, but the memory will, I assume. Correct?

Thanks for your time.

Hope Santa brought everyone their most sought after tech toy. http://www.PCGuide.com/ubb/biggrin.gif

Big Blue 66


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Reach high, for stars lie hidden in your soul. Dream deep, for every dream precedes the goal.
- Pamela Vault Starr

[iisbob]

The settings for yor front side bus will be in the BIOS; hence if it detects your CPU is capable of runing at 133, it'll give the option of increasing the FSB to 133>, when it autodetects your CPU's capabilities it sets the avaiable FSB speed(s).

Of course there are exceptions to this rule, but mostly it's true-for instance, I have a PCChips board that only " oficially " supoorts 100 mhz on the FSB, hence the T-bird i have on it runs at 200; however there is the oprtion for me to push the speeds up to 112, in effect giving mw a FSB of 224-and i've enabled my memory clock to host dram speed +33 ( giving it the 133 memory speed support-my FSB settings have also had the affect of OCing my Memory to effectively 150 mhz.

I would go with the 133 memory simply because any FSB options you have in your BIOS that allows you to bump it up will benefit from the faster memory speed specs ( less chance of it not booting ), just make sure you set the peripheral speed to 0, or no change-PCI and AGP cards don't take kindly to speed increases, this is the major problem with FSB OCing.

Did i give you enough detail? http://www.PCGuide.com/ubb/smile.gif



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iisbob
""I was gratified to be able to answer promptly, and I did. I said I didn't know."
Mark Twain

[BigBlue66]

Hmmm Ok, thanks iisbob.

Let me explain a little further. First, I'm not sure what options I have in BIOS. Basically, my questions are at the motherboard level for right now.

There is a jumper on the motherboard that I can either set to 100Mhz or 133Mhz. My question is, do I set it to 133Mhz, now that I will have all PC133 RAM in the system? I think I should.

I realize that the bus speed is doubled at the processor level, which means I could run a 266Mhz FSB processor if I have the jumper set to 133Mhz. Correct? Thing is, all my processors are 200Mhz, so I won't benefit there, but I should benefit by setting it to 133Mhz because the memory is 133Mhz. Correct?

Now that brings up another question. If I set it to 133Mhz and it's doubled at the processor level to 266Mhz, will I do any harm to my little old 200Mhz FSB processor?

I have seen some other posts that kind of ask the same question, or close to it, so by throwing out my specific question, maybe we can help everyone nail this thing down.

Looking forward to some more replies.

Cheers,

Big Blue 66


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Reach high, for stars lie hidden in your soul. Dream deep, for every dream precedes the goal.
- Pamela Vault Starr

[kenja]

My $00.02: I think moving the FSB jumper to 133MHz will increase the speed of the CPU by a third. The system RAM runs at the FSB frequency by default, but many motherboard BIOSes allow changing the memory bus by +/-33MHz.

For example, my VIA KT133 chipset socket A motherboards allow running (PC133) memory at 133MHz with "200MHz" FSB processors. As I recall, this setting is under "Advanced Chipset Features" in Award BIOSes.

On the Intel platform, I have the FSB jumper set for 100MHz, which means my (default 66MHz FSB) 366MHz Celeron runs at 550MHz. The SDRAM would run at 100MHz by default, but my BIOS allows increasing the memory bus by 33MHz, so I've got the PC133 running at 133MHz. (The (FSB) bus from the Northbridge to the CPU is still 100MHz, so Sandra benchmark scores split the difference between PC100 and PC133 for my chipset.)

I like JadedC36's reply (http://www.pcguide.com/ubb/Forum8/HTML/000544.html) about busses.

Edit: (Saw your reply) Overclockers can increase the CPU speed of a 200MHz CPU by just using the mobo jumper (no "unlocking" required). I doubt that my 750MHz Duron would run at a gig without seriously jacking up the core voltage, so I haven't tried it. If I unlocked the CPU and used a smaller multiplier, it might work with the "266MHz" FSB. People have trouble with this because the most common configuration is to have the FSB jumpered on the mobo and the multiplier adjusted in BIOS. The trouble is, getting through the POST (Power On Self Test); the CPU initially boots up with its default multiplier, ignoring the BIOS setting until later. I've seen an OC site that detailed how to short some of the "L" jumpers to achieve a lower initial multiplier. Anyway, if both the FSB and the multiplier are adjusted with jumpers or both are adjusted in the BIOS, no additional "pencil tricks" are needed on the CPU.

My short reply: Leave the FSB jumper @ 100MHz. Change the BIOS DRAM clock setting to +33MHz (sometimes seen as "> HOST Clock").


[This message has been edited by kenja (edited 12-26-2001).]

[BigBlue66]

Hey thanks, Kenja. I will have to check the BIOS options to see if I even have that DRAM option you're talking about. The motherboard in question is the FIC AZ31, OEM UWAVE version, and from what I remember, the BIOS is whittled down somewhat, and I'm thinking my only options are going to be the jumper on the mobo.

Thanks again.

Cheers,

Big Blue 66


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Reach high, for stars lie hidden in your soul. Dream deep, for every dream precedes the goal.
- Pamela Vault Starr

[BigBlue66]

BUMP.

So, which jumper people? Pete, MJC, RD, Ghost, Fixr, Reid, heisbob, etc.????

BB 66

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Reach high, for stars lie hidden in your soul. Dream deep, for every dream precedes the goal.
- Pamela Vault Starr

[ErnieK]

BB
"Gygabyte" has a wee program on its site called "eay tunnel" as far as I know this will allow you to do what you want from within windows. Not to sure though as I have never done what you are asking. I will send you the PDF file (300kb) giving its details if you want. If I remember correctly the program file is about 1.5Mb

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Ernie

[ranchdog]

Blue...

The 100/133 jumper on the Mboard will have to be set at 100 because you are using a B model chip. If you set it at 133 it's not going to boot up. Example: B Model 1hz built in default is 10x multiplier/100 Bus speed. The 900 is 9x100. The 800 is 8x100. Etc Etc. These chips will not boot with the jumper set at 133 Bus Speed.

There are ways to make this chip function with a jumper setting of 133 but it isn't worth the hassle.

Now the C Model chip can boot with a jumper setting of 100 (instead of 133) but it will be underclocked.

This has always been confusing for people. As people confuse this jumper to be used for RAM speed.

Memory timing (RAM speed) needs to be done in BIOS. If RAM timings are limited in BIOS then a person has to bite the bullet. Although running PC133 is a good idea regardless. If nothing else it will give you some headroom if you can't do any more than let things run with the 100 FSB on the Mboard.

Now here's where he fun begins. With a BIOS that has some options the FSB is adjustable after the 100 FSB jumper is set. Bump it up in BIOS until things become unstable then back off a notch. If you bump the FSB too far and it won't boot up, don't worry about it. Pull the CMOS battery and send everything back to default then start over.

Your Mboard is pretty much a clone to the one iisbob has however he is running little different BIOS. Some of the options may be similar tho.

Luck.


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....How long is a minute... depends on which side of the Bathroom door you're on. ......Indecision may or may not be my problem......
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[This message has been edited by ranchdog (edited 12-27-2001).]

[BigBlue66]

Many thanks, RD. That was the kind of answer I was after. http://www.PCGuide.com/ubb/smile.gif

BB 66

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Reach high, for stars lie hidden in your soul. Dream deep, for every dream precedes the goal.
- Pamela Vault Starr

[iisbob]

Sorry Blue i thought i explained it pretty good-guess not? http://www.PCGuide.com/ubb/frown.gif

but basicly i was telling you just what the other guys said-that your only OCing FSB options are BIOS,not hardware with that board.

Hmmm, maybe i need to speak in ya'll bubba terms in the future so people won't scratch their heads and say; huh??!! http://www.PCGuide.com/ubb/biggrin.gif

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iisbob
""I was gratified to be able to answer promptly, and I did. I said I didn't know."
Mark Twain

[BigBlue66]

iisbob Hey, you explained it very nicely, but I was too stupid to figure it out. When you started talking about BIOS options, I kind of tuned it out, 'cause I knew my BIOS options were limited because of the OEM version of the motherboard. I was just itching to mess with that jumper though. Don'tcha see? http://www.PCGuide.com/ubb/biggrin.gif

RD explained it the way I could understand it, and the way I knew it was all this time, but I just didn't make the connection. Hell to get old.

Now I understand that if I had a 266Mhz FSB processor, I would then set that jumper to the 133Mhz mark. http://www.PCGuide.com/ubb/biggrin.gif

Cheers,

Big Blue 66


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Reach high, for stars lie hidden in your soul. Dream deep, for every dream precedes the goal.
- Pamela Vault Starr

[Paleo Pete]

Huh??? http://www.PCGuide.com/ubb/biggrin.gif

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[iropnman]

Originally posted by BigBlue66:
Hmmm Ok, thanks iisbob.

Let me explain a little further. First, I'm not sure what options I have in BIOS. Basically, my questions are at the motherboard level for right now.

There is a jumper on the motherboard that I can either set to 100Mhz or 133Mhz. My question is, do I set it to 133Mhz, now that I will have all PC133 RAM in the system? I think I should.

I realize that the bus speed is doubled at the processor level, which means I could run a 266Mhz FSB processor if I have the jumper set to 133Mhz. Correct? Thing is, all my processors are 200Mhz, so I won't benefit there, but I should benefit by setting it to 133Mhz because the memory is 133Mhz. Correct?

Now that brings up another question. If I set it to 133Mhz and it's doubled at the processor level to 266Mhz, will I do any harm to my little old 200Mhz FSB processor?

I have seen some other posts that kind of ask the same question, or close to it, so by throwing out my specific question, maybe we can help everyone nail this thing down.

Looking forward to some more replies.

Cheers,

Big Blue 66


FIRST OFF YES SET THE SPEED TO 133 OR THE RAM WILL ONLY RUN AT 100 AS FAR AS THE OTHER QUESTION THE PROCESSOR WILL ONLY RUN AT 200 BECAUSEIT IS NOT A 266 FSB PROCESSOR THE ONLY WAY IT WOULD RUN AT 266 IS IF YOU AHDTHE 266 MHZ FSB CPU PLUS THE RAM WILL NOT RUN AT 266 ANAYWAY UNLESS IT IS DDR RAM AND THE BOARD WOULD HAVETO HAVE SLOTS FOR THE DDR RAM BECAUSETHEY ARENOT THE SAME AS THE SDRAM SLOTS. HOPE THAT THIS WILL HELP IRONMAN

[ranchdog]

Pardon me?

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....How long is a minute... depends on which side of the Bathroom door you're on. ......Indecision may or may not be my problem......
..........

[iisbob]

Nice of you to drop a line iron guy, but please understand what the subject is about and what the subject entails before you start attempting to answer the question. We all know how the CPU and FSB bus works to set the speed-and we all know how the address/data bus on a DDR system is duoblepumped-we were not discussing that, nor does his board support it.



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iisbob
""I was gratified to be able to answer promptly, and I did. I said I didn't know."
Mark Twain

[This message has been edited by iisbob (edited 12-28-2001).]

[BigBlue66]

Um, thanks iropnman

Hey, could ya do us a favor? Try not to use all capital letters. It's hard for us old codgers to read and besides that, capital letters usually signify that you are yelling at us. You're not really yelling at us are ya?

Oh, and please use the Post Reply button at the bottom of the screen rather than replying with the quote, unless you have a specific reason to quote something.

A little puntucation would be nice. Run on sentences are hard to read, too. http://www.PCGuide.com/ubb/confused.gif

Cheers,

Big Blue 66


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Reach high, for stars lie hidden in your soul. Dream deep, for every dream precedes the goal.
- Pamela Vault Starr