Can't buy a single core processor for a new machine I'm building where the recipient wants Windows XP Pro as the operating system. None are available. Have to buy a dual core.
Am I right? - That only vista can utilise both cores when multitasking. XP will use only one of the cores as it cannot handle the hyperthreading technology.
So instead of using say an Intel Pentium 4 3.4GHz (available last year)I have to use an Intel dual core 2.4GHz (available now). So with XP loaded there is effectively less speed than there was with the single core.?

http://support.microsoft.com/kb/810231

That Intel Dual Core will be faster than the Pentium.

Jules said:


XP can indeed utilise dual core processors, and can indeed allocate seperate threads per core. Its not totally multi-core aware though.

However, the OS should not be the main concern for a multi-core environment, more the software that will be used.

But aside from that, the current dual cores (even at much slower frequencies) are much faster (even in single core scenario's) than the older P4's, use less eneergy, & output less heat.

Hi Dublin
Thanks for your post.
Can you refer me to any articles to read on the hyperthreading that XP CAN do please.

Jules said:


I cannot think of any articles off hand.

But as I stated, its really the software that you'll be running that take advantage of multiple cores, not the OS (desktop varieties anyway).

Why are you concerned with XP multithreading? (well, in essence is is multi threaded, but not multi core aware)

AFAIK from SP2 and upwards, XP can indeed recignise and utilise properly, multi-core processors.

i.e. It may run an apllication on one core, while using the other for background tasks.

**edit

Also, hyper threading, and multi-threading are not the same.

Hyperthreading was a process whereby certain Intel P4 based CPU's would fool the OS into thinking there was more than 1 physical CPU installed in the system. This offered a boost on performance in some apps, such as video encoding etc (apps that are historically multi-threaded, and multi-core aware).

Having two physical cores (i.e. dual core) is a far superior solution. As there actually ARE 2 cores available to do the processing.

I'm running a system on XP Pro that is using 2 Xeon processors and running in 4 core mode. So your request for support is that XP does support multiprocessing, but seems to cap out at 4 processors, whether they be virtual/logical or specific.
Server products now support up to 16 processors, but require a Datacenter License in order to support more than that.

Gerritt

Thans for the discussion folk.
Well here's another observation/question.
In system properties, XP does not report a dual core, but Vista does
Why?

What does CPU-z or CBID show about the cores while you're running under XP?

You probably need an updated driver.


BTW, here's something some folks may not know about with running multi-cores on XP:
http://support.microsoft.com/kb/896256
Additional updates are available to optimize performance and behavior on computers that are running Windows XP SP2. Without these updates...dual-core processors may experience decreased performance or unexpected behavior.

Is that the problem relating to AMD X2 processors?

As John stated, it may be a CPU driver issue, or HyperThreading may not be enabled in the BIOS / Device Manager

I'm not sure on this but didn't early (pre SP1) versions of XP home not support multicore chips? But then they unlocked them to a maximum of two cores (logical or physical) once the whole hyperthreading and mulitcore thing got started.? I thought I remember reading that somewhere...

Jim H said:

I think you're right about versions up to and including SP1 not providing multi-core support. However, with the correct and updated drivers, XP (all versions) will support a quad-core processor as far as I know.

Hi Guys
My questions are 'general' ones. (Not a specific problem - just educating myself)
I thought that Dual cores listed the GHz of both cores eg 2.40GHz 2.39GHz when I looked at a Dual core machine.
But I may be mistaken, because when I look at the report on a single core processor with Vista it reports 'Intel(R) Pentium(r)4 CPU 3.00GHz 3.01GHz

But in XP SP3 the same machine reports Intel pentium 4 processor 3.00 GHz
(This machine has two Hard disks with different operating systems)

Some Pentium 4 processors have one physical core (Northwood or Prescott) and one virtual core (Hyper Threading). Windows XP/Vista only sees the physical core, the virtual core is mostly disabled (via the BIOS). Hyper Threading is often abbreviated "HT" in the BIOS. It may take a BIOS update to make the Hyper Threading options available.

Windows XP Home Edition supports up to 32 cpu cores, I'm using a Quad cpu and it works fine. Now I think you need the Pro edition if you're planning to use with Dual cpu's which are different from dual core cpu's which is only on processor with two cores in it.

So why does Vista have two numbers for a Processor frequency eg 2.4GHz and 2.39GHz
And XP (pro) lists one number eg 2.4GHz.

Jules,
This is not Vista specific, but how your system is configured and opperating.
If you see this in CPU-z or in task manager, this is just the differential in how they are being reported, not utilized. The 10% difference is just in the reporting, and how the report is generated, not associated with the actual throughput of the individual cores.

Jules said:

Vista was finished and executed after dual core CPU's were on the market, so it is just how the software was written to show the user the system's CPU. It is nothing significant what so ever. I am sure someone could edit XP to do the exact same thing.

I just read this thread. Of course XP can run dual cores & quad cores.
I have used both amd/intel dual/quad cores on xp.No probs at all.
Any processor albiet single/multi core will run on XP. Why shoudn't it?

Tam the Bam said:


Its not whether the CPU will work - it certainly should, but whether the OS will recognise more than 1 core, and utilise it is the question.

And XP before SP2 did not

Dublin Gunner Said:



Ah right, ok fair play. I didn't have a dual core cpu until after SP2 was released
anyways, so i didn't or wouldn't have known.
But, for anyone to have XP still and not have SP2 is pretty much impossible.
But yea, point granted.

Jules said:
That's actually because the first number is the stock or default clockspeed. The second number is the actual real time clockspeed.

Here's mine in Vista. The first number shows the stock clockspeed of 2.13Ghz. The second number reads 3.2Ghz because my CPU is overclocked. On a non overclocked system this speed could be the same as stock or even slightly less.
http://i12.photobucket.com/albums/a228/waterdrop006/sp1properties.jpg

However in XP, only the actual clockspeed is shown. The default/stock clockspeed is not shown in XP like it is in Vista. Here is what my brother's Althon 64 3000+ shows in XP. It's stock at 1.8Ghz, but overclocked to 2.4Ghz. It shows 2.4Ghz since that is the actual realtime clockspeed.
http://i12.photobucket.com/albums/a228/waterdrop006/random/a64.jpg

So to answer your question, Vista is not showing the speeds of two different cores, its simply showing the expected/default/stock clockspeed and then the actual clockspeed. If your seeing 2.4Ghz 2.39Ghz in Vista's Properties window that means your 2.4Ghz CPU is running at 2.39Ghz.