Can someone please explain to me all this AMD stuff?

[Shooters]

Okay, I'm going to be building my first AMD system in the near future, but I want to understand all this stuff before I do, so here goes.

I know that AMD cpus run at a 200MHz FSB, but I've also been told that it's actually 100MHz but it effectively runs at 200MHz. So, a 800MHz T-bird is setup on the mobo as 100MHz x 8 not 200MHz x 4 right?

Assuming that the above is true, then is there no difference between using PC100 RAM and PC133 RAM since the FSB is actually 100MHz?

I see a lot of people buying mobos with the new KT133A chipset, but I don't see any 133MHz FSB Thunderbirds. Are they on the way? If you're going to get a mobo which supports a 133MHz FSB, then wouldn't you have to have a cpu with a 133MHz FSB to maximize performance?

Thanks,
Shooters

 

[Tzen]

There is a way to unlock the 100MHz FSB processors to make them run at 133MHz. I am not sure how it's done, maybe someone else can explain this? I would like to know as well. I am pretty sure most KT133A boards can run at 100MHz and 133MHz FSB, so it would work anyway. I've only seen a couple of 133MHz processors for sale on the web. Sorry I was not much help.

Tzen

 

[LickEmSmack]

Your first supposition is correct. Currently *most* AMD CPUs are clocked to run at a 100MHz FSB (double pumped to the CPU for 200MHz). Recently, VIA has come oput with the KT133A chipset which actually allows FSB speeds at and beyond 133 MHz (for 266 double pump). For these mobos, AMD has now started making "266 MHz" chips, i.e. instead of 10x100 for 1 GHz, it's 7.5x133 for 997.5 MHz or ~ 1GHz. You can now buy these chips if you like. You can also use the old 200 MHz chips and just unlock them, because they are physically identical (except for their multipliers). This is what I did. Originally, my chip was locked at 10x100, but my man compuwiz1 unlocked it using the conductive pen trick and now I run it at 9x136 for 1224 MHz.

For the 200 MHz boards (VIA KT133 chipset), you *can* use PC100 memory, but I would only get one of these boards if you already have PC100, otherwise I would go for a KT133A board and PC133 RAM since their prices are now virtually identical. The KT133A is pin compatible with the KT133 so new mobo designs are not really needed, and that's why so many have come out recently.

Any more questions?

 

[Grendel99]

If you connect the L1 bridges on the Athlon/Duron CPUs you can unlock the multiplier. So you can make a 1 ghz Tbird (10x100), run on a 133 fsb (133 x 7.5). And the official 133 fsb Tbirds are just coming out. They're a little more expensive than the 100 fsb ones. And I'm pretty sure you cannot run a 100 mhz fsb tbird on a KT133a chipset without unlocking and lowering the multiplier and upping the FSB. Hope that helps some.

 

[Zeeliv]

You don't need a KT133A board to run your memory at 133Mhz. Every Athlon chipset except the original AMD 750 (and the new 760 actually...but that's for DDR memory) have been able to run memory asynchronously from the FSB (ie: they can run memory at 133Mhz while running your FSB at 100/200Mhz).

 

[Shooters]

LickEmSmack, so on a KT133 board there is no difference between PC100 RAM and PC133 RAM provided that you haven't overclocked the FSB? You say that the 200MHz FSB cpus and the 266MHz FSB cpus are identical except for the multiplier, but I've seen people unlocking the multiplier for quite some time now. How come no one has overclocked the FSB to 266MHz until the introduction of the KT133A chipset? I'm going to be building a T-bird 800MHz system for someone, so you're saying that I can just change the multiplier to 6 and ramp up the FSB to 133MHz with a KT133A board? Why not just leave the multiplier alone and kick up the FSB to 133MHz for a speed of 1066MHz similar to what I've done to my PIII 700@933?

Thanks,
Shooters

 

[Shooters]

Okay, just read Zeeliv's post. So, there is a performance gain with PC133 RAM on a KT133 board since the RAM can run at a different speed as the FSB.

Any answers to my post above?

 

[limsandy]

Yeah, it's actually running at 100 MHz. Therefore, you can use PC100 memory modules to run with a AMD CPU. I personally recommend a high quality memory modules, you won't regret it. I bought a good quality memory from memman.com

I got 2 sticks of PC133 256MB memory Infineon modules from them and I am running happily at 150 MHz CAS2 with all eye-candies switched on(4-way interleaving).

Anyway, AMD CPUs are overclockable with adequate cooling. At this time, I am running a Duron 650 @ 975 MHz stable, using the FOP32 hsf.

Just think that the CPU are running at 100 MHz, 200 MHz virtually (coz it's double-pumped to increase memory bandwidth).

 

[twong82]

The KT133 boards do not like high bus speeds and the KT133A has this problem fixed. Before on the KT133, you would be lucky if you could get 112 FSb and now on the KT133A chipset you can get 145+fsb.

 

[Shooters]

Okay, now I'm getting a little confused. Limsandy, you say that you can use PC100 RAM with an AMD cpu, but your RAM is running at 150MHz. How is that possible? So, your system is faster than one with PC100 RAM? Is this the asynchronously thing that Zeeliv was talking about?

 

[Zeeliv]

<< How come no one has overclocked the FSB to 266MHz until the introduction of the KT133A chipset? >>



That was just something inherent in the KT133 chipset...it just didn't run FSB's higher than around 114 or so well at all. There are a few freak cases here and there of people running theirs higher, but it just generally wasn't done until the KT133A.



<< but your RAM is running at 150MHz. How is that possible? So, your system is faster than one with PC100 RAM? Is this the asynchronously thing that Zeeliv was talking about >>



Looks to me like he's just running his 650 at 6.5 x 150Mhz FSB (on a KT133A board of course, because a KT133 board wouldn't be able to handle that FSB) and running his memory synchronously with his FSB.

 

[limsandy]

I told you I bought very high quality memory from memman.com and I also used ABIT KT7A with KT133A chipset which makes AMD CPUs running at 145+++ MHz possible.

 

[Shooters]

Okay, I thought you were still using a KT133 board.

I got one more question. The KT133A chipset just came out, and people are all over it. DDR has been out for a little longer. How come people aren't flocking towards that? Is the KT133A close enough to it in performance to justify not spending the extra cash for DDR?

 

[limsandy]

Zeeliv

I don't think you know a lot about this stuff either.

In my previous UNEDITED post, I said:
&quot;I am running a Duron 650 @ 975&quot;

This means that originally the Duron was running at 650 MHz. Then, I overclock it up to 975 MHz (use calculator to calculate 6.5 X 150). You should get the magic number.

 

[Zeeliv]

Because all the good DDR gear is still limited in availability (or not even out yet) and hence a little more. Once more 760 boards are out (right now there's like 3 crappy ones out) there'll be some of higher quality, and once DDR is more available PC2100 will go down in price to be just a little more than PC1600 (which is really cheap).

EDIT: Lim, that is exactly what I said genius. I do know what I'm talking about.

 

[Passions]

What does FSB of 100mhz and &quot;200mhz virtually&quot; exactly mean? A bit confussed

 

[Shooters]

Okay, last question.....I mean it this time. If the 133MHz FSB Thunderbirds are in fact the exact same as the 100MHz FSB Thunderbirds with just a different multiplier, then why didn't AMD release these a long time ago. Is it just because there wasn't a 133MHz chipset available?

 

[limsandy]

&quot;The KT133A chipset just came out, and people are all over it. DDR has been out for a little longer. How come people aren't flocking towards that? Is the KT133A close enough to it in performance to justify not spending the extra cash for DDR?&quot;

You're damn right the KT133A chipset just came out, but this chipset has been reviewed many times by the overclocker's community and it has been discovered that the KT133A chipset allows FSB tweaking through the BIOS. Increasing CPU speed by increasing its FSB is known to be more beneficial as it provides wider memory bandwidth.

You're damn right the DDR has been out for a little longer. But again, the overclocker's community wants something that's cheap but performs well, therefore overclocking comes into mind. Since the price of SDRAM has taken a deep dive lasy year, it is now officially DIRT CHEAP.

And yes, reviewers found out that DDR systems only perform about 10-20 percent better than SDRAM systems today...... simply because today's software doesn't see the need for the wider bandwidth DDR systems provide. But put this in your mind. DDR systems are bound to perform better than SDRAM in the future. By how much? I don't have the power to see into the future so I can't tell you.

The bottom line is that go for a SDRAM system (WITH HIGH QUALITY RAMs) if you're building a computer in the next 30 days.

 

[LickEmSmack]

True, with the KT133 chipset, you can run the memory asyncronously from the FSB at 133 MHz. I was a little off in my last post. But, most of the improved performance is seen in the increased FSB. This is why people are loving the KT133A and not the 760 DDR chipset. It gives good improvements in performance while using cheap RAM. That and there are plenty of good boards out there with KT133A chipsets, but only mediocre bards with the 760 DDR (except for maybe the ASUS, I think... but that mught be the ALi chipset...)

 

[limsandy]

&quot;If the 133MHz FSB Thunderbirds are in fact the exact same as the 100MHz FSB Thunderbirds with just a different multiplier, then why didn't AMD release these a long time ago. Is it just because there wasn't a 133MHz chipset available?&quot;

YOU'RE DAMN RIGHT! You see..... I believe that Intel have 2 GHz Willy. But if Intel releases the P4 2.000 GHz tomorrow, who would buy the 1.7 GHz, 1.8 GHz and the 1.9 GHz P4 ???

 

[limsandy]

For SDRAM memory, I would recommend getting Crucial modules. A lot of people have reported success in running at 150 MHz, CAS2. Even better, you'll get free shiping

Linkingfied

 

[Shooters]

Thanks for the info. Yeah, I know all about Crucial.....they're awesome. I have some of their memory in my system right now.

 

[CTweak]

[BOBBY RIBS: Here's a 'sum up' of the KT133 and KT133A chipsets and the TBird/Duron's ...

The chipset (KT133) runs the processor bus at 100MHz, but it sends data on both the 'rising' and 'trailing' edge of that signal. Hence, double the amount of data is being sent over the bus, which means it's 'effectively' 200MHz. That's why many people get confused.

The KT133A runs the processor bus at 133MHz, again 'double pumping' the signal to get an effective rate of 266MHz.

Further confusion arose because the KT133 chipset, although it could only run the processor bus at 100Mhz(or maybe 105-112 overclocked) it COULD run the memory bus at 133Mhz for additional memory performance. So you could either run your 100MHz processor with PC100 ram and keep the memory bus at 100 also, or you could buy PC133 and run your 100Mhz processor with the memory at 133MHz.

The Tbirds that officially run the 133MHz bus speed of the so far are no different from the official 100MHz processors, they just have a different multiplier set. Many people here are running unlocked '100Mhz' processors on the new KT133A chipset at 133MHz+ bus speed no problem. Seems to be no compelling reason to get an official 133MHz processor unless you are unwilling, unable, or just don?t want to fool with unlocking the processor.

What you say?!

 

[CoderFirstClass]

There is a good reason to buy an &quot;official&quot; 133MHz Athlon-C T-bird. Warranty. As in, you void the warranty when you overclock the processor. So buy the official one with a warranty, then overclock it when the warranty runs out. That's what I plan on doing.

 

[nortexoid]

1) KT133 boards use 100mhz ddr fsb (200 effective) and can use 100mhz or 133mhz memory (at 133mzh memory, the fsb and memory run asynchronously)

2) KT133A boards can use 100mhz or 133mhz fsb (200 or 266 effective) and can use 100mhz or 133mhz memory (running either synchronously or asynchronously depending if memory and fsb are running at the same frequency)

therefore, u can buy 200mhz athlons and run them on kt133a boards without unlocking the multiplier, just run it at 100mhz fsb...or u can unlock the multplier by unlocking the l1 bridges, which is comprehensively outlined in an anandtech article (under cpus i think)...

both chips/chipsets also tolerate moderate urination, etc...