200/266 Athlons: What's the difference?

funkychild · 6th July 2001, 11:42 AM

What exactly is the difference between the 200Mhz and the 266Mhz Athlons? Is it just the default speeds?

I have been currently running my (unlocked of course) 1Ghz AXIA @ 1.4Ghz on my KT133 board, 112FSB (though it's set to 108 in the BIOS

) with a multiplier of 12.5. Today I received an MSI K7T266Pro DDR mobo and will be using that from now on with crucial/micron PC2100 RAM. What is stopping me from running my chip with a lower multiplier and 133 (266 DDR) Mhz FSB? Anything? Nothing?

I thought that only the final core frequency made a difference for the CPU itself and that differences in the FSB only affected RAM, PCI etc.

Is it just that in the later Athlons they changed the default multipliers and FSB settings to default to 133Mhz fsb selection?

G e n o c | d e · 6th July 2001, 12:26 PM

All the new chips come in two choices, 133fsb (266) or 100fsb (200). Since you have a kt133 m/b, it doesn't support 133fsb so you won't be able to run the 133fsb chips.

At the same clock speed, the 133fsb will out perform the 100fsb cpu, so it's better to have a higher fsb.

Nothing is stopping you to run at a lower multiplier with a higher fsb on your new mobo, in fact, it will produce better performance.

funkychild · 6th July 2001, 12:36 PM

Yes I know I know... But I'm wondering if it's actually necessary to have a 266 Athlon CPU to run at 266Mhz DDR on my new mobo.

I'm not buying a new CPU as I'm perfectly happy with my 1G AXIA (200-FSB-rating) that is doing 1.4 on my old kt133 board.

Brody · 6th July 2001, 3:26 PM

its not needed at all,
it would just be faster if it did.

u have a 100mhz bus chip,
as a simple example.
50mhz in,
50 out,

with a 133 DDR tbird,

its 133 in,
133 out,

understand?

Manaz · 6th July 2001, 4:06 PM

All Athons and Durons run on a DDR FSB. Officially, it actually only runs at 100MHz/133MHz, but because it's DDR, it's often said to be 200MHz/266MHz.

Let's take a 1200MHz Athlon as an example. There are actually 2 versions - one that runs with a multiplier of 12x, and an FSB of 100MHz, and another that runs with a multiplier of 9x, and an FSB of 133MHz.

Assuming your 1200MHz Athlon (either a 100MHz FSB or 133MHz FSB version) is multiplier unlocked (and I believe they all are),you can take it and run it the other way - ie if you have a 12x 100MHz processor, you should be able to change the multiplier to 9x, the FSB to 133MHz (assuming your motherboard supports this FSB speed), and still have a 1200MHz processor. Similarily, if you take a 9x 133MHz processor, and change the multiplier to 12x, and move the FSB down to 100MHz, you will again have a 1200MHz processor.

Now, which is better? Well, the lower your multiplier, and higher your FSB, for a given speed, the better the performance you'll get. So you would expect a 1200MHz Athlon, running at 9x133MHz to outperform a 1200MHz Athlon running at 12x100MHz.

DrClaw · 6th July 2001, 6:42 PM

AFAIK, If you want to do this, you have to unlock the chip, and set the multiplier using the links.

Why?

Well, on some motherboards, the CPU boots up at it's default Mhz setting, and then after a short period of time, the BIOS Multiplier and/or FSB settings are applied :

ie with a 1200Mhz CPU (12.0 x 100) and you overclock it to 1400Mhz, it boots up initially at 1200, then the changes are applied.

The problems begin when you use the 133Mhz FSB, and the CPU initially tries to start up at 12x133 = 1596Mhz. Assuning your CPU can handle this, you'll be ok

I can't remember which motherboard this occurs on, it was up at anandtech somewhere a month or two back. Just be warned

I'd be interested to see how you go btw

HTH

funkychild · 6th July 2001, 11:16 PM

Just about to switch is all over - will post results+benchies when I finish

Squozen · 7th July 2001, 12:56 PM

Quote:

Originally posted by DrClaw
AFAIK, If you want to do this, you have to unlock the chip, and set the multiplier using the links.

Why?

Well, on some motherboards, the CPU boots up at it's default Mhz setting, and then after a short period of time, the BIOS Multiplier and/or FSB settings are applied :

ie with a 1200Mhz CPU (12.0 x 100) and you overclock it to 1400Mhz, it boots up initially at 1200, then the changes are applied.

The problems begin when you use the 133Mhz FSB, and the CPU initially tries to start up at 12x133 = 1596Mhz. Assuning your CPU can handle this, you'll be ok

I can't remember which motherboard this occurs on, it was up at anandtech somewhere a month or two back. Just be warned

I'd be interested to see how you go btw

HTH

This happens on the Asus SDR boards - the Abit boards boot up correctly, so if you're planning to O/C really violently, the Abits are a better choice. Not sure if the Asus DDR boards have the same prob.

--
S

xsive · 7th July 2001, 6:23 PM

Quote:

Originally posted by Squozen

This happens on the Asus SDR boards - the Abit boards boot up correctly, so if you're planning to O/C really violently, the Abits are a better choice. Not sure if the Asus DDR boards have the same prob.

--
S

as i remember, this happens on ALL boards which use a 100/133 jumper - this includes Iwill's KK266, Gigabyte's 7ZX & Epox 8KTA3.. & not ASUS provided you're running in jumperfree mode.

funkychild · 8th July 2001, 7:59 PM

Quote:

Originally posted by DrClaw
I'd be interested to see how you go btw

HTH

Making a new thread with my results now..

6th July 2001, 11:42 AM	#1
funkychild Member Join Date: Jun 2001 Location: Sydney, AU Posts: 678	200/266 Athlons: What's the difference? What exactly is the difference between the 200Mhz and the 266Mhz Athlons? Is it just the default speeds? I have been currently running my (unlocked of course) 1Ghz AXIA @ 1.4Ghz on my KT133 board, 112FSB (though it's set to 108 in the BIOS ) with a multiplier of 12.5. Today I received an MSI K7T266Pro DDR mobo and will be using that from now on with crucial/micron PC2100 RAM. What is stopping me from running my chip with a lower multiplier and 133 (266 DDR) Mhz FSB? Anything? Nothing? I thought that only the final core frequency made a difference for the CPU itself and that differences in the FSB only affected RAM, PCI etc. Is it just that in the later Athlons they changed the default multipliers and FSB settings to default to 133Mhz fsb selection? __________________ Assumption is the mother of all fuckups.

6th July 2001, 12:36 PM	#3
funkychild Member Join Date: Jun 2001 Location: Sydney, AU Posts: 678	Yes I know I know... But I'm wondering if it's actually necessary to have a 266 Athlon CPU to run at 266Mhz DDR on my new mobo. I'm not buying a new CPU as I'm perfectly happy with my 1G AXIA (200-FSB-rating) that is doing 1.4 on my old kt133 board. __________________ Assumption is the mother of all fuckups.

6th July 2001, 11:16 PM	#7
funkychild Member Join Date: Jun 2001 Location: Sydney, AU Posts: 678	Just about to switch is all over - will post results+benchies when I finish __________________ Assumption is the mother of all fuckups.

6th July 2001, 12:26 PM	#2
G e n o c \| d e Member Join Date: Jun 2001 Location: Sydney Posts: 333	All the new chips come in two choices, 133fsb (266) or 100fsb (200). Since you have a kt133 m/b, it doesn't support 133fsb so you won't be able to run the 133fsb chips. At the same clock speed, the 133fsb will out perform the 100fsb cpu, so it's better to have a higher fsb. Nothing is stopping you to run at a lower multiplier with a higher fsb on your new mobo, in fact, it will produce better performance.

6th July 2001, 3:26 PM	#4
Brody Member Join Date: Jun 2001 Posts: 345	its not needed at all, it would just be faster if it did. u have a 100mhz bus chip, as a simple example. 50mhz in, 50 out, with a 133 DDR tbird, its 133 in, 133 out, understand?

6th July 2001, 4:06 PM	#5
Manaz (Damned or Belated) Join Date: Jun 2001 Location: Sydney, Australia Posts: 4,797	All Athons and Durons run on a DDR FSB. Officially, it actually only runs at 100MHz/133MHz, but because it's DDR, it's often said to be 200MHz/266MHz. Let's take a 1200MHz Athlon as an example. There are actually 2 versions - one that runs with a multiplier of 12x, and an FSB of 100MHz, and another that runs with a multiplier of 9x, and an FSB of 133MHz. Assuming your 1200MHz Athlon (either a 100MHz FSB or 133MHz FSB version) is multiplier unlocked (and I believe they all are),you can take it and run it the other way - ie if you have a 12x 100MHz processor, you should be able to change the multiplier to 9x, the FSB to 133MHz (assuming your motherboard supports this FSB speed), and still have a 1200MHz processor. Similarily, if you take a 9x 133MHz processor, and change the multiplier to 12x, and move the FSB down to 100MHz, you will again have a 1200MHz processor. Now, which is better? Well, the lower your multiplier, and higher your FSB, for a given speed, the better the performance you'll get. So you would expect a 1200MHz Athlon, running at 9x133MHz to outperform a 1200MHz Athlon running at 12x100MHz.

6th July 2001, 6:42 PM	#6
DrClaw Member Join Date: Jun 2001 Location: Melbourne, VIC Posts: 911	AFAIK, If you want to do this, you have to unlock the chip, and set the multiplier using the links. Why? Well, on some motherboards, the CPU boots up at it's default Mhz setting, and then after a short period of time, the BIOS Multiplier and/or FSB settings are applied : ie with a 1200Mhz CPU (12.0 x 100) and you overclock it to 1400Mhz, it boots up initially at 1200, then the changes are applied. The problems begin when you use the 133Mhz FSB, and the CPU initially tries to start up at 12x133 = 1596Mhz. Assuning your CPU can handle this, you'll be ok I can't remember which motherboard this occurs on, it was up at anandtech somewhere a month or two back. Just be warned I'd be interested to see how you go btw HTH