# I have a dual core, what now? **URL:** \ **Category:** Factual Questions\ **Created:** [February 11, 2007, 1:59am UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689 "2007-02-11T01:59:14Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![Epimetheus](https://avatars.discourse-cdn.com/v4/letter/e/c4cdca/32.png) [@Epimetheus](https://boards.straightdope.com/u/Epimetheus)\ **Post date:** [February 11, 2007, 1:59am UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689/1 "2007-02-11T01:59:14Z")
I bought a motherboard and Pentium D 820 2 MB Dual core processor, the motherboard supports dual core according to it’s manual, but my task manager is showing one CPU. Do I have to do something special to get it to register as a dual core processor, or am I doing something wrong? ---
**Author:** ![Rysto](https://avatars.discourse-cdn.com/v4/letter/r/ecccb3/32.png) [@Rysto](https://boards.straightdope.com/u/Rysto)\ **Post date:** [February 11, 2007, 2:54am UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689/2 "2007-02-11T02:54:58Z")
What operating system are you running? Windows XP Home does not support dual-core. ---
**Author:** ![Epimetheus](https://avatars.discourse-cdn.com/v4/letter/e/c4cdca/32.png) [@Epimetheus](https://boards.straightdope.com/u/Epimetheus)\ **Post date:** [February 11, 2007, 5:08am UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689/3 "2007-02-11T05:08:10Z")
I have windows XP Pro, but it is a students edition, does that affect it? ---
**Author:** ![yabob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yabob/32/2821_2.png) [@yabob](https://boards.straightdope.com/u/yabob)\ **Post date:** [February 11, 2007, 5:09am UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689/4 "2007-02-11T05:09:59Z")
If your OS does support it, you may have to update your HAL settings to multiprocessor if you are using an existing windows installation. Open the device manager, and look at the setting under “computer”. If it says “uniprocessor”, you need to install the multiprocessor HAL. Clicking properties on that node will give you a “driver” tab, and allow you to select a new driver. Be very careful to select one that will work with your system. You should choose one with the exact same properties as your existing one, with “multiprocessor” instead of “uniprocessor”. You will need your install disk. MS Knowledge Base on the topic: [http://support.microsoft.com/kb/309283](http://support.microsoft.com/kb/309283) I did it on a Win2K system and it worked fine. And unless your new motherboard is nearly identical to your existing system, it’s a good idea to reinstall Windows anyway, which should install the right HAL. ---
**Author:** ![mhendo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mhendo/32/3159_2.png) [@mhendo](https://boards.straightdope.com/u/mhendo)\ **Post date:** [February 11, 2007, 5:14am UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689/5 "2007-02-11T05:14:44Z")
It’s my understanding that: a) WinXP Home does indeed support dual-core processors b) a dual-core processor is still a single processor, and will display as such. c) WinXP Pro will support dual-core processors, and will also support dual processors. That is, it will support two cores on a single cpu (dual-core on one motherboard socket), and will also support dual cpus each in its own socket on the motherboard. WinXP home will NOT support dual processors. ---
**Author:** ![Queuing](https://avatars.discourse-cdn.com/v4/letter/q/90ced4/32.png) [@Queuing](https://boards.straightdope.com/u/Queuing)\ **Post date:** [February 11, 2007, 5:17am UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689/6 "2007-02-11T05:17:39Z")
Dual core shows as 2 processors in the task manger performance tab. ---
**Author:** ![yabob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yabob/32/2821_2.png) [@yabob](https://boards.straightdope.com/u/yabob)\ **Post date:** [February 11, 2007, 5:27am UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689/7 "2007-02-11T05:27:35Z")
> [@](#): > > b) a dual-core processor is still a single processor, and will display as such. I have a dual core processor (not two separate processors), and it shows up as two CPUs in the task manager, as it should. Win2K, as I mentioned, but the results on XP should be the same if a multiprocessor HAL is installed. I had to update that to see both processors when I switched out a single core CPU with a dual one without reinstalling windows. ---
**Author:** ![Rysto](https://avatars.discourse-cdn.com/v4/letter/r/ecccb3/32.png) [@Rysto](https://boards.straightdope.com/u/Rysto)\ **Post date:** [February 11, 2007, 5:58am UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689/8 "2007-02-11T05:58:22Z")
[QUOTE=mhendo] a) WinXP Home does indeed support dual-core processors [/QUOTE] Ah, my mistake, I misread a confusing bit on Wikipedia. If I’m reading it right(and I’m not at all confident that I am), dual-core systems are supported, but dual-processor systems are not. ---
**Author:** ![RandomLetterAssortment](https://avatars.discourse-cdn.com/v4/letter/r/9d8465/32.png) [@RandomLetterAssortment](https://boards.straightdope.com/u/RandomLetterAssortment)\ **Post date:** [February 11, 2007, 4:01pm UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689/9 "2007-02-11T16:01:38Z")
[QUOTE=Rysto] Ah, my mistake, I misread a confusing bit on Wikipedia. If I’m reading it right(and I’m not at all confident that I am), dual-core systems are supported, but dual-processor systems are not. [/QUOTE] You are correct - Microsoft licenses by the socket, not the number of cores. XP Home supports 1 socket, XP Pro 2 sockets. You could run XP Home with a Quad core chip if you wished, or XP Pro with a pair of Quad cores. ---
**Author:** ![Epimetheus](https://avatars.discourse-cdn.com/v4/letter/e/c4cdca/32.png) [@Epimetheus](https://boards.straightdope.com/u/Epimetheus)\ **Post date:** [February 11, 2007, 4:32pm UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689/10 "2007-02-11T16:32:50Z")
[QUOTE=yabob] If your OS does support it, you may have to update your HAL settings to multiprocessor if you are using an existing windows installation. [/quote] I did as you instructed, but it already says ACPI Multiprocessor PC, but then it says that on my laptop, which isn’t a dual core. > [@](#): > > And unless your new motherboard is nearly identical to your existing system, it’s a good idea to reinstall Windows anyway, which should install the right HAL. I got a new, bigger hard drive, so I formatted it and did a fresh install of everything. My fear is that I got ripped off on ebay and was sent a normal processor, here is my winning [auciton](http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=018&sspagename=STRK%3AMEWN%3AIT&viewitem=&item=280075710323&rd=1&rd=1): Unfortunately, while the processor speeds match, my BUS speed says 200 Mhz, not 800. ---
**Author:** ![yabob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yabob/32/2821_2.png) [@yabob](https://boards.straightdope.com/u/yabob)\ **Post date:** [February 11, 2007, 5:30pm UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689/11 "2007-02-11T17:30:45Z")
> [@](#): > > I did as you instructed, but it already says ACPI Multiprocessor PC, but then it says that on my laptop, which isn’t a dual core. Multiprocessor HAL will support a single processor or core, so you can just do a “multiprocessor” install of Windows all the time. It’s theoretically more efficient to install the single-processor HAL if you only actually have one CPU with one core, but I suspect it really doesn’t make much difference. OK, that’s not your problem then. ---
**Author:** ![Mindfield](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mindfield/32/19759_2.png) [@Mindfield](https://boards.straightdope.com/u/Mindfield)\ **Post date:** [February 11, 2007, 5:55pm UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689/12 "2007-02-11T17:55:18Z")
When I upgraded to an Athlon 64 X2 dual core I had a hell of a time trying to get XP Pro (SP2) to recognize the second core. It simply wouldn’t install the multiprocessor HAL. What I ended up having to do was perform a clean install (new motherboard, had to anyway) and manually forcing the multiprocessor HAL during the setup process (IIRC by pressing F5 during the initial setup phase). It worked though; my current CPU driver reads “ACPI Multiprocessor PC” ---
**Author:** ![flex727](https://avatars.discourse-cdn.com/v4/letter/f/258eb7/32.png) [@flex727](https://boards.straightdope.com/u/flex727)\ **Post date:** [February 11, 2007, 7:34pm UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689/13 "2007-02-11T19:34:12Z")
[QUOTE=Epimetheus] My fear is that I got ripped off on ebay and was sent a normal processor, here is my winning [auciton](http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=018&sspagename=STRK%3AMEWN%3AIT&viewitem=&item=280075710323&rd=1&rd=1): Unfortunately, while the processor speeds match, my BUS speed says 200 Mhz, not 800. [/QUOTE] If the processor you received matches the description on the auction page, it is indeed a dual core. Here is Intel’s page on the [Pentium D Processor](http://www.intel.com/products/processor/pentium_d/index.htm). Here is a [review](http://www.pcper.com/article.php?aid=145&type=expert) by PC Perspective. If in doubt, run [CPU-Z](http://www.cpuid.org/cpuz.php). ---
**Author:** ![Epimetheus](https://avatars.discourse-cdn.com/v4/letter/e/c4cdca/32.png) [@Epimetheus](https://boards.straightdope.com/u/Epimetheus)\ **Post date:** [February 11, 2007, 9:02pm UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689/14 "2007-02-11T21:02:13Z")
I wrote the guy and he assured me that it was a dual core, I mentioned to him that Windows (and Belarc Advisor) lists it as running a 200 Mhz bus and he said that Pentium D doesn’t have a 200 and it was likely my motherboard. My motherboard was selected because it supports dual core (ECS P4800Pro-M V.2). He suggest a bios update, but if I mess it up, I am SOL on my motherboard right? ---
**Author:** ![Epimetheus](https://avatars.discourse-cdn.com/v4/letter/e/c4cdca/32.png) [@Epimetheus](https://boards.straightdope.com/u/Epimetheus)\ **Post date:** [February 11, 2007, 9:07pm UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689/15 "2007-02-11T21:07:50Z")
Oh, I like that CPU-Z. It [shows](http://i55.photobucket.com/albums/g122/dgilfoy/cpu-z.jpg) me having an Intel Pentium D 820. ---
**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\ **Post date:** [February 11, 2007, 10:21pm UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689/16 "2007-02-11T22:21:29Z")
Have you got Hyperthreading turned off in the BIOS? Turn it on. I had a very similar problem (identical except I use XP Pro) and that was the solution. ---
**Author:** ![flex727](https://avatars.discourse-cdn.com/v4/letter/f/258eb7/32.png) [@flex727](https://boards.straightdope.com/u/flex727)\ **Post date:** [February 11, 2007, 10:47pm UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689/17 "2007-02-11T22:47:17Z")
Try going into the BIOS setup and see if there is a setting for FSB or check the MB manual for a jumper setting. ---
**Author:** ![Epimetheus](https://avatars.discourse-cdn.com/v4/letter/e/c4cdca/32.png) [@Epimetheus](https://boards.straightdope.com/u/Epimetheus)\ **Post date:** [February 11, 2007, 11:13pm UTC](https://boards.straightdope.com/t/i-have-a-dual-core-what-now/391689/18 "2007-02-11T23:13:55Z")
My BIOS has no options that deal with Hyperthreading or any mention of FSB. My manual also doesn’t mention any jumper settings, and the ECS website has nothing on jumper settings. What is frustrating is that I picked this motherboard out because it says on the website and in the manual that it supports Dual Core Pentium D, Intel, yadda yadda, and that it automatically senses the processing and bus speeds. Apparently it doesn’t. I am going to write Tech support I guess.