Topic awaiting preservation: New computer! And a question about processors...

Well, I ordered and recieved my new computer from Dell:

- Windows XP
- 80 GB hard drive
- 1 GB RAM
- ATI Radeon 9800 (Warcraft runs sooo smoothly on this thing it's crazy)
- lots of random specs that I can't think of right now

I reinstalled Windows last night, partitioning my hard drive into a 10GB drive for Windows/Program Files, and 70 GB for my personal files.

OK, here's the thing. I believe I ordered a 2.6 ghz Pentium 4.

So, I was all excited to see how fast POV-Ray would run on this, and I fired it up and started rendering. It seemed to be faster.

But I hit ctrl+alt+del, and it looked like POV-Ray was only being given half of the processor power. I wasn't too happy with that. After some investigation, I realized that the Device Manager says that I have two processors: both 2.6 ghz. Under "Processors", "Intel(R) Pentium(R) 4 CPU 2.60GHz" appears twice. As POV-Ray cannot run on multiple processors, it would make sense that I have two - that explains why POV-Ray is only using half the power.

So, my question is, is it possible that Windows is simply screwing up, and thinking my single processor is two processors? Or is this my lucky day and Dell gave me twice as much computing power as I asked for? Or, as a third option, did Dell give me two 1.3 ghz processors, pretending it was a single 2.6 ghz processor? And is there any way I could find this out for myself? How reliable is the Device Manager for this? Taking the device manager literally, I have 5.2 ghz at my fingertips; but I'm skeptical.

Thoughts?

....open up the case, I'm sure you'll see theres only one processor (what you'll actually see is an enormous heatsink with a fan on it, but only one of them). My guess is its some sort of software issue. Check your bios settings, however just to be sure - I assume that all Bios are flashed, and loaded new while the computer is being built, but I guess theres the chance that they setup some of it by hand.

What you can be sure of is that Dell didn't give you two 1.3 ghz chipsets. The motherboard support for these would severely limit the capabilities of your video card, asides from the bottleneck from the CPU, and it would display as 1.3ghz, instead of 2.6, even if there was two.

Maybe you have one of those fancy new P4s with Hyper-Threading technology? ...

thats also what i thought of. are there already 2.6 ghz with hyper threading out? if yes, and you got one, then that's just normal

PORTFOLIO0

well, I know hyper threading has been 'brought down' from the 3.06 ghz ones... so it's quite possible for you to have one, slime.

Basically, a modern processer has lots of more or less independant sub units.
Usually, one program will never be able to use all of those sub units at 100% all of the time.
So Intel added a little more, and voila, you got two virtual processors, which mean Pov-Ray will still run as fast as if it was running alone (I believe it was mostly fpu calulations, wasn't it), while you could still surf the net.

Yeh thats what I thought one of the new cpus with hyper threading and tunneling etc...
well you couold check out the guts of the beast but being a ready to rumble box it could be finnicky as Dell arent to keen on having customers poke around indide their pinnacles of technical acheivement. thats why my pc is hand built by me that way I know whats in it spares are ez to get and I can do what I want with it !!!

yehaa ride em cowboy


Razer Force

Duh, open it up and look inside it. I'll do that when I get home today. =)

It's frustrating though, because I want POV-Ray to use *all* of the processor's power without having to run two instances. Is it impossible to make the computer consider it to be a single processor?

Is it simply that the processor has so many pipelines that it can't efficiently use all of them at once unless it's running separate processes?

Could it have anything to do with the virtual memory settings?
I've just doubled the ram to approximately 450mg with an 800 celeron (win2kpro the OS btw) and I'm still trying to figure out paging file size that works well. There are some things like 'liquify' in PS that seem slower now than with win98 & 200megs ram.And that's with 'Optimize performance for:' set to "Applications.' For sure a cold boot and running any program after a cold boot is unbelievably slow. Driving me a bit nuts.

Anyway probably nothing to do with it but pass it on just in case. =)

As you said, Dan, there's only one heatsink in there, so I guess there's only one processor.

TP, you said "Pov-Ray will still run as fast as if it was running alone" - do you mean that running two instances of POV-Ray (which causes them to take up nearly all of the processor power - other things slow down very noticeably) will *not* get more accomplished than running a single instance?

yup, you've got an HT processor which is handled by w2k and XP as dual processor. I'm not sure if you can change that or not. I think when I first had a read about HT when it first came out it mentioned Win2k and XP treating it as 2 processors by *default*. If my memory is right on that word, it would imply that you *can* change it.

very interesting observation and question there, I couldn't think of a scenario where the HT would be a bad thing but you may have just found it

off to Tom's hardware...

Jason

edit: have a look in the OS's help files. The Microsoft Knowledgebase has some interesting articles if you search on hypertherading or dual processors, particularly "Cannot Run Certain Programs on Hyper-Threaded or Dual-Processor Computers with a CPU Speed of Greater Than 2 GHz". I couldn't find anything on being able to use the processor as a single, in fact, I think I lied when I said w2k would run them, inconclusive there, but NT OSes support dual processors and I could have sworn I had read that they would recognize an HT chip as a dual.

Let us know what happens, very interesting.

[This message has been edited by JKMabry (edited 08-08-2003).]

Well, I did some google-research on hyperthreading, and it appears that this is nothing but an advantage.

Apparently, the pentium pretends to be two processors, so that existing operating systems which already support dual processors don't have to be changed at all to work with it. Internally, it's only a single processor which keeps track of two processor "states" (registers and some other stuff). When one process stalls (because of a cache miss or a branch misprediction or something), it starts sending the other process through.

So, I believe, a single copy of POV-Ray on this 2.6 ghz processor would go the same speed as a different 2.6 ghz processor *without* hyperthreading. But if I run another process, it fills in the "holes" that the first process leaves, essentially giving me an extra bonus in execution speed that the other processor wouldn't be able to provide.

To take full advantage of this, I'll have to run two copies of POV-Ray (or download the patch someone wrote which supports multithreading), but if I choose not to do so it's not like I'm wasting half of the processor power.

I wish the Windows task manager reflected this, but what can you do.

Anyway, I'm happy now. Thanks for all of your pointers!

While it's true that in most cases, hyper-threading is an advantage, some tests have proved that it can actually degrade performance on certain applications.

An article: http://www.pcmag.com/article2/0,4149,699649,00.asp

quote:

---

PC Magazine:

There can be instances where two applications are both contending for CPU resources, or when one app is doing far more work than the other. Hyper-Threading could actually be a hindrance to performance at such times. For example, when we encoded a movie in the foreground (using Windows Movie Encoder) and ran WinZip on a large number of files in the background, we saw a 16 percent drop in performance with Hyper-Threading enabled. This is a big reason why your new 3.06-GHz systems will have a switch in the BIOS that will allow you to turn Hyper-Threading on or off.

---

2.6GHz is the lowest clock speed Intel pushed the HT down to, so you're lucky

And you should be able to turn it off in the BIOS if it ever causes problems.

Yeah, I should run some tests to see if it's really faster to run two instances of POV-Ray, or other things that I do.

By the way, I think intel.com said that there were 2.4 ghz processors with HT.

well, yes, with or without ht, the 2.6ghz will run povray at about the same speed.

Now, as for 'running two instances of povray at the same time'.
Give it a try!
Based on my assupmtions, they'd hinder each other (since they use the same part of your processor),
but they might just alternate between different parts, which the one not using part a at this moment using b, and the one not using b using a, and so on...

Well, I did a quick test on this scene:

camera {

	location -z*10

	look_at 0

}



#include "functions.inc"



plane {

	z,0

	pigment {

		function{f_noise3d(x,y,z)}

		scale .03

	}

}



light_source {

	<-3,2,-3>

	rgb 1.5

}

One instance of POV-Ray rendered this scene with high anti-aliasing settings in 36 seconds; two instances simultaneously rendered it in 1 minute 22 seconds. Ouch. Guess it didn't work out too well.

I should try that patch and see what results it has.

(Fixing scrambled UBB-generated page)

Sorry if I'm being redundant here (don't have much time to read the earlier replies). WinXP recognizes my 3.0 Ghz as "2" processors as well (with Hyper-Threading). My motherboard's BIOS settings allow me to disable it however. If you are thinking of disabling it, trying the BIOS settings can't hurt. Good luck...

http://www.intel.com/english/home/customize/build/components/bios.htm