I still don't get it...

[Lemming]

I'm wondering what sort of advantage I get by buying a 133fsb tbird as opposed to a 100fsb tbird. As I understand it, all you gotta do is unlock the 100fsb tbird (unless it runs stable with the set multiplier and 133fsb) and it should run perfectly on the 133fsb...

Another question is: will a 100fsb tbird do over 133fsb? something like 140 or 150?
And will the memory bus be affected by that sort of increase? Will the PC133 CAS3 memory I intend to buy do?

 

[1sikbITCH]

An 800mhz cpu w/100mhz fsb has a clock multiplier ratio of X8 (100 X 8= 800)
An 800mhz cpu w/133mhz fsb has a clock multiplier ratio of X6 (133 X 6= roughly 800)
That means that if you overclock the 100mhz to 110 you should get 110 X 8= 880 This can be slightly more or less because the 800 is actually not a precise measurement (could be 798 or 802, etc).
If you overclock the 133mhz to 143 you can only expect 143 X 6= 858.
The higher you set the fsb, the bigger the difference between the two.
So for overclocking the 100mhz is better.

 

[1sikbITCH]

Also I have an old microstar mobo that has clock speeds up to 155. That doesn't mean the cpu can handle it. Mine can't go past 115 (yet ).
About the ram, the speed of the fsb is translated to everything that runs off the mobo since the mobo is now running faster. Your ram may or may not handle it. I would say screw the cas3 and get cas2 instead. That will definately have a better chance of handling the overclocking. If the cas3 can't hang you are just going to go buy cas2 anyway.

 

[MGMorden]

But he stated in his original post that he was going to unlock the chip, so the intended multiplier is irrelevant. (i.e., he could run either chip at 8x110, or 6x125)

 

[Lemming]

ok, let me clarify my questions:
I'm going to buy a new system in the near future consisting of the following basic components:

VIA KT133A based mobo (probably the msi turbo)
AMD tbird probably 900 MHz, possibly 1 GHz
128MB PC133 cas3 RAM

the questions I have are:
If I go with the 1GHz, should I buy the 200MHz or the 266MHz fsb version? and why?

Will I be able to run the 200MHz version on a 133fsb after unlocking the cpu and lowering the multiplier? I'm not even talking about OC'ing the cpu right now (i.e. 133x7.5 instead of 100x10)

Will I have problems with the RAM under these conditions? I know CAS2 would be better, but over here in Austria it costs about twice as much as CAS3, so I would like to avoid it if possible.

What about running on an even higher fsb (140-150)?

 

[GaryTcs]

An unlocked 200mhz T-bird may or may not run at 266 fsb. Since the 266 bus part has access to 33% more memory cycles at the same speed, this is the one to get. Provided the price reflects the 10% or so performance increase expected. Cas3 ram will run fine so long as it's rated as PC-133, and you do not intend to oc the bus. It may become flaky beyond that if it's poor quality.(my Cas3 rated ram does 147mhz no problem.)

 

[Molochi]

Link to HardOCP review of KT7A with a TBird 750/100@1120/140! This is the only mobo I've seen that will use SDRAM with the KT133A chipset (msi turbo?) though others are sure to surface.

 

[mikef208]

Molochi, what other type of RAM do you expect the kt133a boards to use.


Also from what I understand a 100mhz Tbird, should work fine on the kt133a