Maximum Cachable RAM

Maximum Cachable RAM

Post by Imitheo » Tue, 31 Jul 2001 06:20:25



Hello.
I want to upgrade my ram (I now have 64MB) and i have read that if you put
more ram than your system can cache, the rest will be useless.
I have a slot-1 pentiumIII-450 (not socket coppermine, the former one.i
think katmai is its name) and my motherboard is a jetway 910af.
Is it the motherboard cache or the cpu cache thats matters ?
How can i see how much ram my system can cache ?
Is there a factor (x kb cache for y mb of ram ) ??

Thank you.

 
 
 

Maximum Cachable RAM

Post by B. Joshua Rose » Tue, 31 Jul 2001 07:13:59


It's possible that your system is limited to 384M but you should check
with the motherboard maker. I have a PII-450 Slot 1 system from Dell and
that one is limited to 384. PIII Coppermines can support 4G.



Quote:> Hello.
> I want to upgrade my ram (I now have 64MB) and i have read that if you
> put more ram than your system can cache, the rest will be useless. I
> have a slot-1 pentiumIII-450 (not socket coppermine, the former one.i
> think katmai is its name) and my motherboard is a jetway 910af. Is it
> the motherboard cache or the cpu cache thats matters ? How can i see how
> much ram my system can cache ? Is there a factor (x kb cache for y mb of
> ram ) ??

> Thank you.


 
 
 

Maximum Cachable RAM

Post by Dances With Cro » Tue, 31 Jul 2001 08:55:25


On Sun, 29 Jul 2001 18:13:59 -0400, B. Joshua Rosen staggered into the
Black Sun and said:



>> I want to upgrade my ram (I now have 64MB) and i have read that if
>> you put more ram than your system can cache, the rest will be
>> useless. I have a slot-1 pentiumIII-450 (not socket coppermine, the
>> former one.i think katmai is its name) and my motherboard is a jetway
>> 910af. Is it the motherboard cache or the cpu cache thats matters ?
>> How can i see how much ram my system can cache ? Is there a factor (x
>> kb cache for y mb of ram ) ??

>It's possible that your system is limited to 384M but you should check
>with the motherboard maker. I have a PII-450 Slot 1 system from Dell and
>that one is limited to 384. PIII Coppermines can support 4G.

(B. Joshua:  Please don't top-post.)

The CPU has nothing to do with the maximum cachable RAM; the motherboard
chipset has much more to do with that.  I would be surprised if your
board can't cache at least 256M.  The maximum cacheable RAM size should
be somewhere in the motherboard manual, assuming you have a motherboard
manual.

--
Matt G|There is no Darkness in Eternity/But only Light too dim for us to see
Brainbench MVP for Linux Admin /     That which does not kill us
http://www.brainbench.com     /      makes us stranger.
-----------------------------/       --Trevor Goodchild, "AEon Flux"

 
 
 

Maximum Cachable RAM

Post by Trevor Hemsl » Tue, 31 Jul 2001 08:56:59



> I want to upgrade my ram (I now have 64MB) and i have read that if you put
> more ram than your system can cache, the rest will be useless.
> I have a slot-1 pentiumIII-450 (not socket coppermine, the former one.i
> think katmai is its name) and my motherboard is a jetway 910af.
> Is it the motherboard cache or the cpu cache thats matters ?

P-II/III motherboards don't have any cache, it's all on the chip.

All P-II's can cache at least 512MB, only the very earliest are
limited to 512MB and most allow 4GB.  All P-III's can cache 4GB.

--
Trevor Hemsley, Brighton, UK.

 
 
 

Maximum Cachable RAM

Post by Aniarti » Tue, 31 Jul 2001 09:03:17



> The CPU has nothing to do with the maximum cachable RAM; the motherboard
> chipset has much more to do with that.

No, that was the case on S7 based systems but with the P-II's and their
on-board cache on a seprate bus it's the domain of the CPU.

Quote:> I would be surprised if your board can't cache at least 256M.  The
> maximum cacheable RAM size should be somewhere in the motherboard manual,
> assuming you have a motherboard manual.

I belive it started off at 512Mb, then went up to 2Gb then finaly 4Gb.

Ani

--
Disclamer:
I reserve the right to be 100% wrong/have malformed &/or biased opinions,
feel free to politely correct me. If however you do not wish to be
courteous go {the remainder of this disclamer has been censored}!

 
 
 

Maximum Cachable RAM

Post by Eric P. McC » Tue, 31 Jul 2001 13:04:10



> I want to upgrade my ram (I now have 64MB) and i have read that if you put
> more ram than your system can cache, the rest will be useless.

It will be used, but will not be as fast as the cacheable area.  This
can result in more memory actually _decreasing_ performance (if you
frequently access memory in the noncacheable region).

Quote:> I have a slot-1 pentiumIII-450 (not socket coppermine, the former one.i
> think katmai is its name) and my motherboard is a jetway 910af.

I have dual P3-450s, also Katmai, on a 440GX-based motherboard.
And...

Quote:> Is it the motherboard cache or the cpu cache thats matters ?

There is no such thing as a motherboard cache on anything newer than
the PPros: they all have an on-die L2 cache.  The cacheable region is
the amount of space addressable by the L2 cache.

Quote:> How can i see how much ram my system can cache ?

According to Intel (http://developer.intel.com/design/PentiumIII/prodbref/):

  Memory cacheability up to 4 GB of addressable memory space and
  system memory scalability up to 64 GB of physical memory.

Note that your chipset almost certainly limits you to far less memory
(1GB if you have a 440BX, 2GB if you have a 440GX; the rest I don't
know).

--

  "Knowing that a lot of people across the world with Geocities sites
absolutely despise me is about the only thing that can add a positive
spin to this situation."  - Something Awful, 1/11/2001

 
 
 

Maximum Cachable RAM

Post by Cyberbea » Tue, 31 Jul 2001 21:08:46



> Hello.
> I want to upgrade my ram (I now have 64MB) and i have read that if you put
> more ram than your system can cache, the rest will be useless.
> I have a slot-1 pentiumIII-450 (not socket coppermine, the former one.i
> think katmai is its name) and my motherboard is a jetway 910af.
> Is it the motherboard cache or the cpu cache thats matters ?
> How can i see how much ram my system can cache ?
> Is there a factor (x kb cache for y mb of ram ) ??

> Thank you.

Older Pentium boards with the VX and TX chipsets had the 64MB limitation.
Boards with the Intel 440BX and later chipsets do not suffer with this
problem.

And, with some OSes it wouldn't matter much anyway, because the memory was
still usable, just slower access. With other OSes, like NT, the memory was
almost useless because of the memory layout that the OS used and how it
allocated memory addresses to the apps it was running.

If you have a PIII board you don't have to worry. Fill that baby with RAM!

 
 
 

Maximum Cachable RAM

Post by Imitheo » Wed, 01 Aug 2001 05:10:10


Informationaly, i use linux and my chipset is i810 (i forgot to mention it).

Thank you all for your answers.
I really apreciate it.
From what i understood, the maximum cachable is 4gb (i thought that was the
maximum addressable thats why i was confused in the first place).

Thank you all.

 
 
 

1. use un-cachable RAM as swap on RAM drive

My system will only cache 64 MB of RAM (I have an ABIT SM5A with Pentium
233MMX, Intel 430VX, 256kB of pipelineburst cache and 96MB RAM). Here's my
question (someone must have thought about this before):

Is it possible to allocate the uncached part of the memory as a RAM drive
and use this drive as part of the virtual memory in order to seperate
cacheble and non-cacheble RAM? Or should I just donate this 32 MB to my
little sister?

Greetings,
remko


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