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Xbox and Celeron CPUs

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LiGhTBoY

Member
Joined
Feb 2, 2002
OK this has nothing to do with overclocking, just info.
Well I was looking at a PC magazine when I came across a table with CPU specs. This table said (listed :) ) that a Pentium III has 256 KB of L2 cache and a Celly 128KB. Well off for a search on Xbox. The search revaled that the CPU of the Xbox has 128 KB of L2 cache. Well....... you draw the conclusions :)

PS
DO correct me if I'm wrong.
 
OP
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LiGhTBoY

Member
Joined
Feb 2, 2002
Yes guys , M$ says it has a p 3 but have you taken a closer look at the pics showing the CPU. It does'n write Pentium III on it . :)
 

FullTower

Registered
Joined
Mar 3, 2002
Location
@ big dog
Actually it's a Pee 3 with 128KB of L2.

The CPU that powers the Xbox is a Coppermine based Pentium III with only 128KB L2 cache. While this would make many think that the processor is indeed a Celeron, one of the key performance factors of the Pentium III that is lost in the Celeron core was left intact for this core. The Coppermine core was left with an 8-way set associative L2 cache instead of the 4-way set associative cache of the Celeron. Based on what we've seen with the Coppermine and Coppermine128 (Celeron) cores we estimate that the 8-way set associative L2 cache gives this particular core a 10% performance advantage over the Coppermine128 core of the Celeron.

The fact that Intel decided to go with a 128KB version of the Coppermine core indicates that there is a way of disabling half of the L2 cache without modifying the mapping associativity. We fully expect the Xbox's CPUs to be nothing more than Coppermine processors with half of their 256KB L2 cache disabled.

The other aspects of the CPU remain unchanged; the core does not have SSE2 support, only support for Intel's SSE instructions. It still has a 16KB L1 instruction cache and 16KB L1 data-cache and also very important is its 133MHz FSB. We've proved time and time again about how critical a high-speed FSB is to overall system performance, and the situation is no different inside a gaming console.


Here is the link to the whole article.

http://anandtech.com/showdoc.html?i=1561&p=2
 
OP
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LiGhTBoY

Member
Joined
Feb 2, 2002
AXIA said:
No!

The XBOX CPU is a Celeron processor @ 733MHz with a 133FSB.

Thats all!


AXIA
I agree with you. It just doesn't make sense to use a more expensive CPU (p III ) . It would be cheaper to use a Celly with 133FSB.
 

brothernod

Member
Joined
Feb 4, 2002
Also, why would the disable part of the l2 cache... that's not economical.
and according to the [H]ardocp writeup on it, it's a modified celeron.
 

Tbird man

Member
Joined
Jun 19, 2001
Location
Boone, NC a.k.a THE BOONIES
I recall hearing in an article a while back where they opened one up and had the same question. as i recall they went looking for answers and at the time (may be different now) MS was quite tight lipped about it. they managed to pry it out of an unnamed intel engineer that knew and they said it was a modified p3. perhaps i am wrong but thats what i remember.
 

Kingslayer

Senior Member
Joined
Jun 12, 2001
Location
Port Charlotte, Florida
It's not more economical for them to use a Celeron than it is a PIII. It COSTS Intel $50 more to make the Celeron than it does the PIII. Disabling half of the cache would probably be cheaper in than using a Celeron.

But I would just throw a complete PIII in there and be done with it, but Microsoft works in mysterious ways.
 

brothernod

Member
Joined
Feb 4, 2002
the only reason I could see to actually go through the trouble of disabling some of the cash is if they're also using p3s that don't meet the p3 spec due to crappy production... then again, that's a celeron now isn't it.

as I said, [H] said it was a modified celeron.

why is the celeron $50 more to make than the p3??

I don't know if it makes a difference, but lets not forget the chip decision was made while the p3 was still very much a flagship chip.