Intel Pentium HyperThread ?

[DVWannaB]

All,

I am considering investing in a HTPC and am a bit confused with the Intel Pentium 4 HyperThread technology. Is it an important development that one should have in their computer processor or is it just some buzz word in ad campaign to get you to buy something that costs more but dont necessarily gain anymore power? Or can I just go with Intel Pentium 4 2.93GHz with 800FSB and 1GB DDR Memory? Thanks.

[jagabo]

Hyperthreading can deliver 10 or 15 percent more performance. It can sometimes deliver less performance than a non-hyperthreading CPU too. You can always disable hyperthreading if it turns out to be a problem.

A 2.93 GHz P4 would have a 533 MHz FSB. I'd spend a few dollars more and get a 3.06 GHz P4 with 800 MHz FSB and hyperthreading.

[MOVIEGEEK]

Yeah I have a P4 with HT but I disable it because it caused too many conflicts.I agree with getting a CPU with a faster FSB.If you're building a HTPC(no encoding) then what you are looking at is overkill,a 2GHz CPU is more than enough.

[SingSing]

Can we disable Hyperthreading in Windows ?

[MOVIEGEEK]

Can we disable Hyperthreading in Windows ?

Not in Windows but you can in your BIOS.

[DVWannaB]

Thanks guys, much appreciated with advice.

[jagabo]

Can we disable Hyperthreading in Windows ?

Not in Windows but you can in your BIOS.

You can also bind a process to a particular CPU (processor affinity in task manager).

[cd090580]

You can try that,

add the following line in your boot.ini:

multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professionnel without Hyperthreading" /noexecute=optin /fastdetect /numcpu=1

look at the sample: I added /numcpu=1

to make sure it will work, open your boot.ini and dupolicate the line juste under [operating system] section and add the /numcpu=1 and change the description.

So at each boot you will have the choice of which version of Windows you want to run.

I hope it will work. I never tried it.

[TBoneit]

jagabo: a 3.06 GHz P4 is a 533 FSb processor, the 3.0 GHz is the 800 FSb processor.

Moving on
I found that HT on my 3.0 did yield a speed boost in encoding video with TMPGEnc 3.0 Xpress and since encoding is what I do that is the most processor intensive I leave it on. And of course if you are doing encoding of Video under XP you can restrict the encoding to one virtual CPU with HT and leave the other Virtual CPU free to run other things speedily. IOWs a HT P4 shows up in windows XP as two 3.0 CPUs. Not the same speed as two separate CPUs of course.

For max Speed if running a Intel then go for the dual core P4.

[kenmo]

Pentium D 805's are very cheap. Wouldn't you gain more performance from two phyisical cpus or dual cores then a phyisical cpu and a logical cpu...???

[jagabo]

Pentium D 805's are very cheap. Wouldn't you gain more performance from two phyisical cpus or dual cores then a phyisical cpu and a logical cpu...???

But if you only run single threaded apps, one at a time, you'll get better performance from a higher clocked P4 for the same price. So, it's all a matter of what software you use and how you use it.

[rallynavvie]

I actually use a dual Athlon 1900 MP machine as an HTPC running Windows MCE and it works just fine. In fact I was also using it for file sharing at one time and it was able to handle the MCE portion just fine. I actually found having a second processor pretty handy. Handy enough that my DH800 with dual 3.06s will be my new HTPC so that I can run the other CPU on video encodes in the background. A dual-core processor would be similarly handy. And if you do what I do and encode your shows down to smaller sizes (I take mine with me when I travel) most encoders will use both those cores. And if my 1900 MPs can handle MCE then as long as each core is at least 2.4 GHz you'd be running just fine. Now if you're gaming you'd want that single core faster CPU. All the same I'd disable HT on any P4 you get. Unless you use a lot of office apps at once you'd see more benefit of it being disabled so applications can see the entire chip.

[bacardi/avt]

I am lost here...why would you even want to dissable HT? What are the exakt benefits of doing that? and what kind of problems have people had with HT?

the reason I am asking is that in my current set-up I run a Intel (socket 478) P4 HT with 800MHZ FSB and have never had any problems since I buílt this machine a year and a half ago (or more can't remember)...It just keeps on going..

[deadrats]

Pentium D 805's are very cheap. Wouldn't you gain more performance from two phyisical cpus or dual cores then a phyisical cpu and a logical cpu...???

the P4 has a 31 stage pipeline, and doesn't do error checking until the 19th stage (at least that's the way it was when the P4 had a 20 stage pipeline).

in all instruction pipelines you get "bubbles", i.e. portions of the pipeline devoid of instructions. when this happens it's known as a stall. the P4, by virtue of it's deep pipeline encounters stalls on a regular basis. hyperthreading is a way (it's used by IBM also) for the P4 to make sure that when a stall does occur that empty space in the pipeline is filled up with instructions from a second thread, thereby maximizing the pipelines efficiently.

the dual core P4's, with the exception of the extreme edition, don't have hyperthreading, so now, instead of having 1 31 stage pipeline with a stall, you have two that can potentially have a stall.

the question really becomes: is it better to have 1 pipeline being used to close to 100 percent effiecency or 2 pipelines used to 70 percent efficiency?

from the point of view of a daily pc, there is no question that a dual core P4 is a much smoother computing experience than a higher clocked single core cpu.

personally i would much rather have a higher clocked single core P4, with HT enabled and a larger L2 than a slower clocked dual core P4, no matter how much cheaper it is.

but it is obvious that you are leaning toward the D 805 and if truth be told, it a good chip at that price point, just don't expect any miracles from a chip that uses a mirrored L2 cache design and 533mhz fsb.

[jagabo]

add the following line in your boot.ini:

multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professionnel without Hyperthreading" /noexecute=optin /fastdetect /numcpu=1

I tried it but it didn't work. So I searched around and found that the argument is /numproc=1. I think you can also use /onecpu. Thanks for the hint though!

[jagabo]

I am lost here...why would you even want to dissable HT? What are the exakt benefits of doing that? and what kind of problems have people had with HT?

Single threaded programs, or programs optimized for multiple CPUs, sometimes run slower with hypthreading enabled. When this happens it's usually only a few percent slower. For example games are usually single threaded and often run faster with hyperthreading disabled.

[edDV]

thought it might be games

[jagabo]

TMPGEnc runs faster on P4s with one thread too. Which is really odd because it runs more than twice as fast on dual core CPUs and two threads.

[rallynavvie]

That's because the dual-core has two processors. I have HT disabled on both my dual Xeon rigs. I noticed about a 15-30% slowdown with HT enabled when using TMPGEnc.

[jagabo]

Yes, it's two cores, but it's more than twice as fast, which is unusual. I ran a test earlier today, encoding a 1 minute DV AVI file to 8000 kbps CBR with my Athlon 64 X2 3800+. With one core disabled (and TMPGEnc running with a single thread) it took 112 seconds. With both cores enabled and TMPGEnc configured for two threads it took 50 seconds.

[bacardi/avt]

So had to do some test with TMPGEnc, I took two different Dolby trailers (train long and Rain) and one uncopressed avi (made with virtualdub from the Microsoft Pinnball HD trailer and these where the results:
Train: 1 tread took 2:16, 2 treads took 2:11
Rain: 1 tread took 1:41 , 2 treads took 1:44
Pinnball: 1 tread took 2:14 , 2 treads took 2:01

Train and Rain encoded as ES 720x480 3000CBR 29,98 fps
Pinnball encoded as ES 720x480 7000CBR 23,97 fps

The strange thing is the Rain trailer where it took longer with 2 treads than 1, but then again this might be due to HDD access. My conclusion (if you can make one only testing small clips like this) is that for me HT seams to be the way to go, still the speed gain isn't that great.

[smearbrick1]

TMPGEnc runs faster on P4s with one thread too. Which is really odd because it runs more than twice as fast on dual core CPUs and two threads.

I think you may be mistaken. My P4 can encode at a faster than realtime with HT enabled but slows down signicantly if disabled. Unfortunately I don't a shred of proof to back this up.

Isn't kind of silly to disable HT just because it may interfere with some processes?

[wayne421]

A word of caution on disabling HyperThreading:

I installed Windows XP Pro with HT ENABLED in the BIOS, and XP detected it as dual-cpu blah blah blah and installed the appropriate drivers.

When I was testing the system later on, I DISABLED HT in the BIOS, and low and behold, Windows wouldn't boot! Just hung up a second before the logo appeared. As soon as I RE-ENABLED HT in the BIOS, Windows booted up happily.

I'm sure this has something to do with how XP installs itself initially (something to do with the HAL or whatever? Can't remember the terminology).

If I'm the only person who's had this problem, than I guess I'm just lucky!

[Eyedoctor2]

For more on disabling HT for a given process see:

http://www.techzonez.com/forums/showthread.php?t=11446

In my case when I used FairUse Wizard last night with HT enabled my CPU temperature soared past 75 degrees and my system was automatically shut off by MSI Core Monitor.

I tried running the program again to see if this was a fluke and I had to stop the program when the CPU reached 73 degrees.

I am going to disable one "processor" tonight and try again.

My computer has never had heat issues before, and I regularly use DVD Rebuilder, CCE and other encoding processes.

[TBoneit]

For more on disabling HT for a given process see:

http://www.techzonez.com/forums/showthread.php?t=11446

In my case when I used FairUse Wizard last night with HT enabled my CPU temperature soared past 75 degrees and my system was automatically shut off by MSI Core Monitor.

I tried running the program again to see if this was a fluke and I had to stop the program when the CPU reached 73 degrees.

I am going to disable one "processor" tonight and try again.

My computer has never had heat issues before, and I regularly use DVD Rebuilder,
CCE and other encoding processes.

Strange. What CPU are you using? I run a P4 3.0GHz, 800FSB with HT enabled. I run TMPGEnc Xpress in batch mode overnight all the time, with other background stuff running. Sometimes I'll start it burning at the same time or Start it suthoring a DVD in TDA right before I turn off the monitor and all three processes complete successfully. Keeping in mind all three are not running at the same time due to authoring or burning accessing the same drive. So it is Encoding and authoring or encoding and burning.

Bottom line if I check the CPU using my digital probe AKA index finger during an encoding session the heat sink is just slightly warm to the touch. I do tend to run my computer with the side off of the case, Lian Li aluminium case with three fans, since that did reduce CPU temerature and becasue I am a tinkerer. Sometimes just for easy repair. I found a bad Samsung SATA HD saturday, approx 2.5 years old. Fired off the email for RMA yesterday morn. couple of hours later had a RMA number and dropped into the UPS yesterday. When it comes back it will go back into service as temp storage use. One thing about Samsung they're in this state, usually less tan one week for ship to them and then they ship back RAM service. Quality is usually OK. I should have waited til SATA tech got more refined. This drive was a early model. 1st one lasted less than a week. I should have been checking disk management more often too as it showed the Samsung as "At Risk" status when I looked rather than the normal healthy. I never looked into it but it appears that XP Pro may be checking S.M.A.R.T. status or else monitoring r/w tries.

[Eyedoctor2]

My CPU is Pentium 2.8 800 FSB, very similar to yours.

Strange indeed.

[rkr1958]

My CPU is Pentium 2.8 800 FSB, very similar to yours.

Strange indeed.

Barton or Northwood core? A Barton core runs significant hotter than Northwood. I have a Northwood P4 2.6-GHZ, 800-MHz FSB. My CPU temperatures under load run around 113-deg F. When idle, CPU temperatures run around 90 to 95-deg F.

[jagabo]

TMPGEnc runs faster on P4s with one thread too. Which is really odd because it runs more than twice as fast on dual core CPUs and two threads.

I think you may be mistaken. My P4 can encode at a faster than realtime with HT enabled but slows down signicantly if disabled. Unfortunately I don't a shred of proof to back this up.

I should have said TMPGEnc can run faster with HT disabled. It depends on the settings you use in TMPGEnc. One setting that makes a difference in relative encoding time is Motion Search Precision. I ran a benchmark this morning on my HT 2.8 GHz P4 converting a 90 second MPG movie trailer. I used the BOOT.INI method (/NUMPROC=1 or 2) to switch between 1 and 2 processors.

With MSP set to "Normal" it took 90 seconds with hyperthreading, 105 seconds without. With MSP set to "Highest Quality (very slow)" it took 409 seconds with hyperthreading 401 seconds without.

Isn't kind of silly to disable HT just because it may interfere with some processes?

Depends. If you run one pokey application all the time and it runs 5 percent faster without hyperthreading it may make sense to disable hyperthreading. Personally, I run my HT P4 and my A64 X2 with both CPUs enabled. Except when I'm running benchmarks comparing 1/2 CPU operations!

[rallynavvie]

Barton or Northwood core? A Barton core runs significant hotter than Northwood. I have a Northwood P4 2.6-GHZ, 800-MHz FSB.

You mean Prescott? Barton was one of the later AMD Athlon XP cores, the last Athlon XP core IIRC.

[strongbad]

Does AUTOGK benefit more from HT or no?