Will a 133 mhz cpu work in a gigabyte GA-6bxc mobo?

[diogenes10]

I have been given a system with a GA-6BXC motherboard.
It currently contains a pentium ii 400 mhz processor.
(Slot 1 type.) It will apparently take a pentium iii processor up to some level.

(I forgot to look at the board revision level - Manual date is April 29, 1999 and board level is consistent with that.)

I don't understand a lot of the terminology here but I have been doing reading and looking on eBay.

What I think I am understanding is that there was a change in the slot 1 processor construction at 600mhz so that if I want to spend more money, the better thing is a 600 or 650 with the "on board" memory, if I want cheap I can go back to 500 or 550 and get one with the "off board memory" maybe trying to find 512 instead of 256.

My problem now is with the next number.

Say the processor says 600\256\100 or 600\256\133 .

My manual gives me conflicting information.

Back in the manual in a section called cpu speed setup it gives a list of 14 processor types
Pentium ii from 233 to 400.
Pentium iii from 450 to 650.

Then I go back to page 2 of the manual. It says:
"The system bus speed is selectable between 66/100 Mhz. The user can select the system bus speed (SW1) and change the DIP SWITCH (SW2) selection to set up the CPU speed for 233-633Mhz processor."

At this point confusion galore starts.

1) The sentence states 233-633.
The table shows a max of 650.
The table for SW2 on page 2 of the manual shows CLK RATIO setting from X3 to X9.5 which would seem to support a higher speed processor than 633 or 650.

2) The sentence says the bus speed is 66/100.
However the table for SW1 contains the following settings under the CPU column
100 Mhz
133 Mhz
112 Mhz
66 Mhz
75 Mhz
83 Mhz

And then contains related agp frequencies and switch positions.

My experimentation experience with pentium processors is only with the square pentium 1 processors in Dell boxes so I have no experience or knowledge that would help me make decisions about the information above.

Based on the SW1 and SW2 table settings it looks to me like I could use a 133Mhz processor (and some of them seem to be a bit cheaper on eBay - a plus for that) and also based on the clock ratio table, if I wanted to pay the extra, I might be able to use a 700 or 800 something processor instead of stopping at 650, but I don't "know" any of that.

Also, I have no idea what real difference there might be in performance from 500 to 650 and from off board to on board memory. For a non-gaming machine I am suspecting it might not be too much.

Any experience or thoughts that would be helpful to me?

Thanks.

 

[rbranco]

Go to the gigabyte site, they updated the bios giving extra options, also there is an updated DIP switch config list.

 

[BadBigBen]

Diogenes10 - I've run a 733 mhz Celeron, with a MSI 6905 FPGA Slot adapter on one of those boards... albeit only at 100mhz.


Ben

"If it works don't fix it! If it doesn't use a sledgehammer..."

 

[felixc]

The manual probably gives what was available at time of publishing. If the mobo lists 133MHz, then any processor with a 133MHz bus should work. You just need to set the right multiplier. At worst, if you can get a 800MHz one, you can just change the multiplier to a lower setting.

I have run AMD K6-2 at 333MHz, on a mobo made for a Pentium MMX-233.

As rbranco says I'd try to get a BIOS update, and the latest version of the manual, from the gigabyte web site. The BIOS update would give a better ID of the newer processors and implement undocumented patches at power-on, to solve some strange behaviors. (one of Intel's little dirty secrets)

 

[cdogg]

Usually the multiplier is locked in Pentium I/II/III CPU's (one of the reasons AMD started gaining favor in the underground during the days of the PII).

Therefore, the FSB (frontside bus) is absolutely critical here. If you throw a 600MHz CPU (133MHz FSB) into a motherboard that only supports up to 100MHz FSB, then the resulting speed will be around 450MHz since the multiplier is locked. This is why this part is so critical to your decision. You must find out for sure what the max FSB setting is for your board. If you go into the BIOS now, see what settings there is for it.


Also, look for a BIOS revision update on Gigabyte's website (if they still post them). Chances are that even though the manual states the max CPU speeds supported, it is outdated and will likely go beyond that with an update.

And finally, PIII slot processors actually went up to 933MHz and 1GHz, but they weren't produced in high numbers and would likely cost more than they're worth even on eBay. 800MHz was generally the cut off point for Intel, where they started to go back to the socket interface for their Coppermine CPU's.

~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Albert Einstein
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884

 

[diogenes10]

I didn't know enough to know this when I asked the question but I guess I was asking an overclocking question.

As I read, what I see is that the cpu speed, the agp speed, and the pci speeds are all linked. I am pretty sure I can choose the 133mhz option for the cpu, but this will also probably overclock the agp and pci ports and give me the risk of ruining items there. Definitely true on the agp port - have read conflicting comments relating to PCI.

It appears the more prudent course would be to stick with the 100fsb processors. At the high end the geek.com table shows 800E and 850E at 1.65 volts and 1000E and 1100E at 1.7 volts in the slot 1 category.

cdogg, thanks for your multiplier statement above. I haven't been understanding that as I have been reading and after rereading your comment 3 or 4 times, it finally clicked in my head what people are saying with that.

Based on other threads I have looked at, I am guessing I could use any of the 100 fsb processors regardless of the limit in the manual, as BadBigBen suggests above.

There are apparently some other options if I go further along the lines of BadBigBen's approach and use a 370 processor (Piii or Celeron) and a slocket. (Piii with a thermaltake fan on a slocket appears to be the high end idea.)

For the moment, as a first step, because of modest price and availability in a local store, I have bought a 600E. This will get me from Pii to Piii.
I am now concerned about the risk of bios upgrade and have posted another question relating to that here:
thread602-1136694 .

(BadBigBen, I am not sure what I need to know about the slocket cards - I may have more questions about that approach.)

 

[BadBigBen]

You can find the information on the Slotket manufacturers Homepages... I know I did aswell... I was at that point you are at now, about the adapter... didn't know 'diddly doo' about it either...

we are a big family here and we like to help, so just ask away and you shall receive an anwer...



Ben

"If it works don't fix it! If it doesn't use a sledgehammer..."

 

[cdogg]

diogenes10,

Yeah, you're right on the money about the FSB being tied directly to PCI and the southbridge on the motherboard. Any speed that you set the FSB that's higher than what the manufacturer intended is going to "overclock" the southbridge, which is what you want to avoid (especially at a 33MHz jump from 100MHz, which would likely ruin any PCI cards you use).

As for processor support...

I'm not sure what led you to believe that any SLOT 1 CPU is going to work on your board. Unless it has been 1) tested or shown in a 2) BIOS upgrade's specs, there's never a guarantee. I would put my money on that it will, but there's no way of knowing for sure unless one of the two cases I just mentioned are true.

As for the slocket...

I've heard many success stories about this. However, again the FSB still plays a role here. I believe all socket 370 CPU's require the 133MHz FSB. So an 800MHz socket 370 PIII, for example, would have a built in multiplier of 6 (133 x 6 = 798).

If that CPU was used on your board with a slocket adapter, my guess is that because of the 100MHz FSB limit, it would only run at 600MHz (100 x 6) since the multiplier would still be locked.

~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Albert Einstein
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884