dual core, 64bit processor/how effect my everyday computing

jimmyj68

Senior member
Mar 18, 2004
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:confused: The market now carries dual core and 64bit capable processors from both Intel and AMD. Also, there is now a 64bitversion of windows. Help me understand the following:

1. if I upgrade winXP to 64bit do I need a 64bit CPU?

2. an upgrade to a dual core CPU is automatice 64bit. Do I need 64bit winXP to run a dual core CPU? How does AMD differences factor in?

3. How much of the vanilla winXP and all the programs I'm presently running will not function with a 64bit CPU or a dual core CPU?

I'm really slow this evening, so go light on the engineering info. Thanks
 

Diogenes2

Platinum Member
Jul 26, 2001
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Originally posted by: jimmyj68
:confused: The market now carries dual core and 64bit capable processors from both Intel and AMD. Also, there is now a 64bitversion of windows. Help me understand the following:

1. if I upgrade winXP to 64bit do I need a 64bit CPU?

There is not an upgrade available per se. You can get the trial version for free, or get it from certain OEMs.

http://www.microsoft.com/windowsxp/64bit/howtobuy/default.mspx

Yes you do need a 64bit CPU.


2. an upgrade to a dual core CPU is automatice 64bit. Do I need 64bit winXP to run a dual core CPU? How does AMD differences factor in?

Im not sure about Intel, but AMD 64's, X2's included, run with virtually everything out there.. They run in 32bit mode until you get a 64 bit operating system.. You do need Win2k Pro or XP pro to run 2 CPU's or 2 cores.. The 2 core AMD will just run one core, if 2 CPU support is not provided in the OS.

3. How much of the vanilla winXP and all the programs I'm presently running will not function with a 64bit CPU or a dual core CPU?

They should all work. They may or may not run any faster, but with two cores, you will benefit from smoother multitasking..

I'm really slow this evening, so go light on the engineering info. Thanks

What hardware are you running Now? Chances are, you will see a lot of improvement, just moving to AMD 64 X2 , and staying with Win2k or XPpro for the next couple of years..

It will probably be a while before the average person will benefit very much from running a 64 bit OS.


The Win XP64 FAQ

http://www.microsoft.com/windowsxp/using/64bit/russel_x64faq.mspx

 

jimmyj68

Senior member
Mar 18, 2004
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Running an intel 865PE motherboard
3.2 gig prescott
2 gigs of ram
raid 0 two Hitachi 80 gig
1 wd 80 gig IDE backup
XFX 6800 video card
Revolution 7.1 sound card
win XP Pro

would a move to a 64bit intel cpu and new motherboard be a good interim measure? For the next year or so?
 

Vee

Senior member
Jun 18, 2004
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Originally posted by: jimmyj68
would a move to a 64bit intel cpu and new motherboard be a good interim measure? For the next year or so?

?

No. You have no use for a 64-bit CPU before you need it to run 64-bit software.
(edit: ) You also have no need for a 64-bit OS before you need it to run 64-bit software. (end edit.)
There are almost no Windows64 applications available today.

You need a 64 bit OS to run 64-bit applications.
A 64-bit OS will also run 32-bit applications.
It will not, however, run old 16-bit applications (which you can run from 32-bit Windows, even with a 64-bit CPU).

A 64-bit CPU is today typically still used as a 32-bit CPU, and it is as such completely identical in function to a 32-bit CPU. The 64-bit ISA is inactive and lies dormant.

Edit: Your 3.2GHz Prescott is basically as good as they will come from Intel for a while yet. You have IMO no significant reason to make any changes now. Not even AMD.
 

Calin

Diamond Member
Apr 9, 2001
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I never knew 64-bit operating systems won't run old 16-bit applications.
You can think somewhat at the 64-bit instructions as just another kind of instruction set extension like the SSE. If your program doesn't know SSE, it won't use it (it is much more complex than that, however it is simpler than the move from 16-bit processors to 32-bit processors).
Also, rewriting/recompiling a program to 64-bit could lead to all kind of performance improvements, like from much faster (let's say) to slower. Why faster? Some things really can be widened to 64-bit. Why slower? Some other things even in 32-bit processors use only 16 or 8 bits. Also, 64-bit has bigger instructions/adresses, so they use more cache, so your cache miss might go up (a bit, some or a lot)

I agree about the 3.2 Prescott being almost as good as any other current choice. Based on your rig, I think you use it mainly for games. In this case, moving to a single core faster Athlon64 might benefit you (but it will cost). Moving to dual core for games is more or less a bad decision (in my opinion)
 

Calin

Diamond Member
Apr 9, 2001
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Originally posted by: jimmyj68
:confused: The market now carries dual core and 64bit capable processors from both Intel and AMD. Also, there is now a 64bitversion of windows. Help me understand the following:

1. if I upgrade winXP to 64bit do I need a 64bit CPU?

2. an upgrade to a dual core CPU is automatice 64bit. Do I need 64bit winXP to run a dual core CPU? How does AMD differences factor in?

3. How much of the vanilla winXP and all the programs I'm presently running will not function with a 64bit CPU or a dual core CPU?

I'm really slow this evening, so go light on the engineering info. Thanks

If you upgrade to 64-bit Windows, you need to upgrade to 64-bit drivers. There should be now 64-bit drivers for everything, but there might be issues
 

Vee

Senior member
Jun 18, 2004
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Originally posted by: Calin
You can think somewhat at the 64-bit instructions as just another kind of instruction set extension like the SSE. If your program doesn't know SSE, it won't use it.

- OMG, NO! 64-bit is not at all like an instruction extension like MMX or SSE.
No offense, but there are lots of myths about various CPU-thingies circulatating. Let's not add to them, even if you're tempted to 'simplify' things for the sake of the OP.

64-bit is really about moving to a completely new CPU. The "X86" has gone through that metamorphosis twice before, '286 and '386. 64-bit is an "extension" in the meaning that the CPU retains backwards compatibility through two different 32-bit 'personalities'.
It is absolutely not an extension in the sense of simply adding instructions.

One of these 32-bit 'personalities' is 'legacy mode' in which the CPU works in a manner identical to previous 32-bit CPUs, '386 through to Pentium4 and AthlonXP. Including these CPUs' backwards 16-bit compatibility with '286 and 8086, - and also their inability to run any 64-bit code. This is how most A64s and 600-P4 operates today, under a 32-bit OS.
The CPU can of course NOT execute 64-bit code from legacy mode.

The other 32-bit personality is the ability to execute 16-bit-pm and 32-bit-pm instructions from its 64-bit 'long mode' through an emulation layer ('compatibility submode') in memory management.
However in this 'long mode' the CPU is NOT operating like previous 32-bit CPUs and is not compatible at lower & higher levels, like adress translation, interrupts, exceptions, or with non protected mode instructions!

A 64-bit OS, of course, runs the CPU in 'long mode'.

(it is much more complex than that, however it is simpler than the move from 16-bit processors to 32-bit processors).

Sorry, I beg to differ again. But it is much, much easier to port software from 32-bit to 64-bit, since both Win32 and Win64 program models use a flat virtual space. I assume you were thinking of that aspect alone?
In other ways, the move to 64-bit from 32-bit is certainly not simpler than 16-bit to 32-bit.

I never knew 64-bit operating systems won't run old 16-bit applications.

I assume this is a decision by Microsoft.
Since the AMD86-64 CPU is not compatible with 8086, '286 real mode, '386 virtual real mode or any 16-bit hardware access, in 'long mode', I can only assume that MS decided to get rid of a lot of luggage and save themselves trouble by dropping 16-bit support completely from Windows64. Theorethically, it seems to me it should be possible to build an OS that runs some very well written and well behaved Windows16 programs, on a 64-bit CPU in 'long mode'.
...But, like, why bother?

Why slower? Some other things even in 32-bit processors use only 16 or 8 bits. Also, 64-bit has bigger instructions/adresses, so they use more cache, so your cache miss might go up (a bit, some or a lot)

Possible performance penalty from 64-bit is not significant enough to be ever worthy of mentioning. It would only be visable in software were there is a direct instruction to instruction correspondance between 32-bit and 64-bit version. That's only how people like SiSoft build their "benchmarks" - until Intel is ready :disgust: - .

A mature 64-bit compiler will put out 64-bit code that is different from 32-bit code and makes use of the new additional true GP registers, and other additional registers for a performance improvement.
It is true that software that makes use of integers longer than 32-bit will achieve a dramatic performance increase from porting to 64-bit (100%-500%). This is not the usual case however, but 64-bit software will still feature a performance increase, maybe 20%-40% compared to most 32-bit software due to other reasons.


(edited for clarity)