32 or 64 bit XEON on the same server?

I've bought this server: IBM eServer xSeries 236 with two XEON.
On the IBM site, it seems that the server supports only 32-bit
processors with Intel EM64T enhancement.
On the Intel site, the two processors (one with S-Spec: SL7ZE and Core
Stepping: N-0 , and one with S-Spec: SL8P5 and Core
Stepping: R-0) seem 64-bit processors.
So the questions are:
1. Can the server run with two different S-Spec and Core Stepping
processors?
2. What kind of Operating System I have to install: 32-bit or 64-bit
compliance?

Thanks in advance for any suggestion.
HS.

* HS:

> I've bought this server: IBM eServer xSeries 236 with two XEON.
> On the IBM site, it seems that the server supports only 32-bit
> processors with Intel EM64T enhancement.

XEONs with EM64T _are_ 64bit XEONs...

> On the Intel site, the two processors (one with S-Spec: SL7ZE and Core
> Stepping: N-0 , and one with S-Spec: SL8P5 and Core
> Stepping: R-0) seem 64-bit processors.
> So the questions are:
> 1. Can the server run with two different S-Spec and Core Stepping
> processors?
> 2. What kind of Operating System I have to install: 32-bit or 64-bit
> compliance?

The XEONs with EM64T can run both 32bit and x64 operating systems. If
you don't have native 64bit applications and/or more than 4GB or memory
you probably want the 32bit version...

Benjamin

HS wrote:
> I've bought this server: IBM eServer xSeries 236 with two XEON.
> On the IBM site, it seems that the server supports only 32-bit
> processors with Intel EM64T enhancement.

If it's got EM64T support, then that's a 64-bit Xeon, not a 32-bit one.

Yousuf Khan

On Wed, 13 Dec 2006 18:43:45 +0100, Benjamin Gawert <>
wrote:

>XEONs with EM64T _are_ 64bit XEONs...

This document (page number 9)
http://download.intel.com/design/Xeo...s/30235501.pdf
speaks about 32-bit XEON with Intel EM64T.

>> On the Intel site, the two processors (one with S-Spec: SL7ZE and Core
>> Stepping: N-0 , and one with S-Spec: SL8P5 and Core
>> Stepping: R-0) seem 64-bit processors.
>> So the questions are:
>> 1. Can the server run with two different S-Spec and Core Stepping
>> processors?
>> 2. What kind of Operating System I have to install: 32-bit or 64-bit
>> compliance?
>
>The XEONs with EM64T can run both 32bit and x64 operating systems. If
>you don't have native 64bit applications and/or more than 4GB or memory
>you probably want the 32bit version...

The server will be a db-server with Red Hat and Oracle and the RAM is
8 GB, so I'll buy 64-bit version.

And what about question number 1?

Thanks,
HS.

* HS:

>> XEONs with EM64T _are_ 64bit XEONs...
>
> This document (page number 9)
> http://download.intel.com/design/Xeo...s/30235501.pdf
> speaks about 32-bit XEON with Intel EM64T.

To be precise, there are no "real" 64bit XEONs (as there are no "real"
64bit Athlons and Opterons). EM64T is an 64bit enhancement to 32bit
XEONs. The same is valid for AMD64 btw, they also are 32bit CPUs with
64bit enhancement. In fact, the "EM64T" is what makes XEONs 64bit.
That's why this document says "...The Intel® Xeon™ processor with 800
MHz system bus supports Intel® Extended Memory 64
Technology (Intel® EM64T) as an enhancement to Intel's IA-32
architecture. This enhancement allows the processor to execute operating
systems and applications written to take advantage of the
64-bit extension technology."

So simply spoken all 800MHz FSB XEONs are 64bit.

> The server will be a db-server with Red Hat and Oracle and the RAM is
> 8 GB, so I'll buy 64-bit version.

Good decision.

Benjamin

On Thu, 14 Dec 2006 06:32:32 +0100, Benjamin Gawert <>
wrote:

>>> XEONs with EM64T _are_ 64bit XEONs...
>>
>> This document (page number 9)
>> http://download.intel.com/design/Xeo...s/30235501.pdf
>> speaks about 32-bit XEON with Intel EM64T.
>
>To be precise, there are no "real" 64bit XEONs .....

I'm not sure of this, as you can see here:
http://download.intel.com/design/Xeo...s/30624902.pdf
it seems that there are native 64-bit XEONS.

Anyway, thanks so much for the answers.

Bye,
HS.

* HS:

>> To be precise, there are no "real" 64bit XEONs .....
>
> I'm not sure of this,

But I am. There are no "real" 64bit x86 processors, neither from intel
nor from AMD. All these 64bit processors are 32bit processors with a
64bit extension.

> as you can see here:
> http://download.intel.com/design/Xeo...s/30624902.pdf
> it seems that there are native 64-bit XEONS.

If you read the text carefully you should notice that these XEONs are
basically the same (32bit XEONs with EM64T enhancement) like the other
ones. Intel just calls them now "64bit XEON" simply because today it's
an important feature while with the older XEONs it was just another
(unused) feature...

As I said, there definitely are no "real" 64bit XEONs. All 800MHz FSB
XEONs (and later) are 64bit enhanced 32bit processors as are AMD64
processors. The "real" current 64bit processor from intel is the Itanium2...

Benjamin

Benjamin Gawert wrote:
> To be precise, there are no "real" 64bit XEONs (as there are no "real"
> 64bit Athlons and Opterons). EM64T is an 64bit enhancement to 32bit
> XEONs. The same is valid for AMD64 btw, they also are 32bit CPUs with
> 64bit enhancement. In fact, the "EM64T" is what makes XEONs 64bit.
> That's why this document says "...The Intel® Xeon™ processor with 800
> MHz system bus supports Intel® Extended Memory 64
> Technology (Intel® EM64T) as an enhancement to Intel's IA-32
> architecture. This enhancement allows the processor to execute operating
> systems and applications written to take advantage of the
> 64-bit extension technology."

Very confusing statement. First you say they aren't "real" 64-bit, and
then you say "EM64T is what makes Xeons 64bit".

It's as simple as saying that there are both 64-bit and 32-bit modes for
these chips. The 64-bit mode is just as real as any other processor's
64-bit mode.

Yousuf Khan

* Yousuf Khan:

>> To be precise, there are no "real" 64bit XEONs (as there are no "real"
>> 64bit Athlons and Opterons). EM64T is an 64bit enhancement to 32bit
>> XEONs. The same is valid for AMD64 btw, they also are 32bit CPUs with
>> 64bit enhancement. In fact, the "EM64T" is what makes XEONs 64bit.
>> That's why this document says "...The Intel® Xeon™ processor with 800
>> MHz system bus supports Intel® Extended Memory 64
>> Technology (Intel® EM64T) as an enhancement to Intel's IA-32
>> architecture. This enhancement allows the processor to execute
>> operating systems and applications written to take advantage of the
>> 64-bit extension technology."
>
> Very confusing statement.

Not really.

> First you say they aren't "real" 64-bit, and
> then you say "EM64T is what makes Xeons 64bit".

Right.

> It's as simple as saying that there are both 64-bit and 32-bit modes for
> these chips. The 64-bit mode is just as real as any other processor's
> 64-bit mode.

Nope. AMD64 processors (and intels CPUs with EM64T) are still 32bit
processors with 64bit extensions. "Real" 64bit processors aren't 32bit
processors with 64bit extensions but are 64bit designs from the beginning.

Of course there is no advantage to have a "real" 64bit CPU over the
64bit enhanced CPUs. But this little difference is important to
understand the intel documents.

Benjamin

On Thu, 14 Dec 2006 21:01:23 +0100, Benjamin Gawert <>
wrote:

>* Yousuf Khan:
>
>>> To be precise, there are no "real" 64bit XEONs (as there are no "real"
>>> 64bit Athlons and Opterons). EM64T is an 64bit enhancement to 32bit
>>> XEONs. The same is valid for AMD64 btw, they also are 32bit CPUs with
>>> 64bit enhancement. In fact, the "EM64T" is what makes XEONs 64bit.
>>> That's why this document says "...The Intel® Xeon™ processor with 800
>>> MHz system bus supports Intel® Extended Memory 64
>>> Technology (Intel® EM64T) as an enhancement to Intel's IA-32
>>> architecture. This enhancement allows the processor to execute
>>> operating systems and applications written to take advantage of the
>>> 64-bit extension technology."
>>
>> Very confusing statement.
>
>Not really.
>
>> First you say they aren't "real" 64-bit, and
>> then you say "EM64T is what makes Xeons 64bit".
>
>Right.
>
>> It's as simple as saying that there are both 64-bit and 32-bit modes for
>> these chips. The 64-bit mode is just as real as any other processor's
>> 64-bit mode.
>
>Nope. AMD64 processors (and intels CPUs with EM64T) are still 32bit
>processors with 64bit extensions. "Real" 64bit processors aren't 32bit
>processors with 64bit extensions but are 64bit designs from the beginning.
>
>Of course there is no advantage to have a "real" 64bit CPU over the
>64bit enhanced CPUs. But this little difference is important to
>understand the intel documents.
>
>Benjamin

Jeez!

The EM64T cpu's have 64 bit architecture, i.e. general purpose
registers are 64 bit. Hence they are 64 bit cpu's.

But they weren't designed from the git-go for 64 bit. The
instruction set is derived from x86-32 but with 64 bit
extensions.

Contrast Itanium I and II which were designed for a
64 bit (only) OS, and with an instruction set unique
to the architecture.

Eh??

Cheers,
Puddin'

Pease pudding hot,
Pease pudding cold,
Pease pudding in the pot
Nine days old ...