Do most of you who've OC'd your i7's disable HT?

I'm a bit of a noob, but I too have been debating this a bit myself, considering the great choices out there for 775 and tumbling prices of the Q9XXX series.

I think when your looking at upgrading to an i7 series, you've also got to look at the investment perspective. The new motherboard socketing is most likely going to fit even the next iteration of motherboards (after the tock series).

You've also got to look at your utilization of cores. When benchmarking, we're usually trying to limit all outside influences on the cpu, therefore, there isn't an anti-virus running, your mp3 software, your instant messaging, all your custom desktop alterations, and for some even stupid background apps crammed onto your computer from the likes of Itunes software and HP printer packaging.

With Vista, and Windows 7 coming soon, we'll see at a minimum the ability of your operation system to take advantage of multiple cores to execute multiple programs much more efficiently. And then games following suit. Right now, you know what is most cost effective, but 12 months from now, you will certainly be upgrading more than just your processor.

Is your gaming RIGHT NOW gonna be effected, mostly likely not. Would you like the ability to have all of the above mentioned apps going while your gaming AND not suffer a degradation in FPS? This is where the i7 will hep contribute. Will it be a total fix, not likely, but it depends where your priority lies, is it in your current gaming philosophy, or would you like to ask more from your CPU?

just my thoughts
 
vanilla_guerilla said:
yes i realize this, it was just a response to the guy who claimed 20% speed increase with ht, and to the guys who claim that they would be able to tell if ht was enabled or disabled while running apps in windows, or it would actually make any real world difference today. this is hardocp. my machine runs faster with ht disabled. there you go. when i am running telemetry for nasa, i will enable ht.
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:rolleyes:
You might get higher clocks, but you actually reduce perfomance overall....kinda retarded, but then again so is everything related to e-penis.
 
http://ixbtlabs.com/articles3/cpu/ci7-turbo-ht-p1.html

Despite its new reincarnation, Hyper-Threading is still as controversial as in times of NetBurst. This technology yields zero performance gains according to our overall score (rounded), even though some tests demonstrate significant performance gains or drops. The reasons are lying on the surface: it's not easy to optimize software for virtual multiprocessing.
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This makes a good argument for disabling HT.
Enabling HT because it is there... is not very convincing!
 
I remember reading at one point that compiling is one of the best case scenarios for HT, showing almost 100% improvement with it enabled... sorry, I don't have a source, this was back in the days of Netburst. Since I'm a developer and I spend a decent amount of time waiting for VS to compile I've always left it on. I figure it can't hurt too much.
 
for most things programmed well, your better off with ht on rather than the higher clockspeed
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The problem is that only a very few apps are optimized for virtual multiprocessing.
However, most apps will benefit from higher clockspeed.
 
Lets put it this way, apps that are optizimed for virtual multiprocessing will see a significant increase in performance (noticable) while the gains of a hundred or two hundred mhz from turning off HT will be very insignificant and won't be that noticable.

But at the end of the day, it's your pc and who cares what someone else says.If you would rather have 4.2ghz with HT off than 4.0ghz with HT on.. more power to you. Personally, while I don't render alot I like to use cinebench as a "stability" tester. Running all 4 cores with 8 threads at 100% seems to be a pretty good workout for my pc and will insta crash if things are unstable. When I run the same tests with HT off it just takes so much longer that I get frustrated :)
 
All depends on what you're using your box to do. Period.

I render, I need 8 VCs. If I didn't render, I'd disable HT and OC 200MHz higher. Simple as that.
 
I notice with HT enabled, my system is somewhat faster for VMs and the like, using VMWare Workstation. Windows startup seems smoother too but maybe its just my perception. I keep it on and am running 4Ghz OC'ed right now.
 
It's interesting to me that in that ixbtlabs review, having HT turned on actually led to a decrease in performance (EDIT: In some cases). Why might that be?

Personally, I use my i7 for a lot of gaming and almost no rendering or number-crunching, and based on the results in that article, it seems like it might be a better idea to turn it off and overclock instead.
 
MavericK96 said:
It's interesting to me that in that ixbtlabs review, having HT turned on actually led to a decrease in performance (EDIT: In some cases). Why might that be?

Personally, I use my i7 for a lot of gaming and almost no rendering or number-crunching, and based on the results in that article, it seems like it might be a better idea to turn it off and overclock instead.
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Again, most multithreaded software isn't programmed to run best on virtual cores, only real cores. And that's multithreaded software. Single threaded software shows no benfit with HT on. In your situation, I'd disable HT, get another 200MHz+ OC and lower your temps.
 
Im pretty sure 20% increase is incorrect. In WCG folding, I get a 30% increase in output if HT is enabled =) This thing goes crazy(meaning insanely fast) in WCG and apps like it that can run full bore on all 8 cores =)
 
imo using a i7 cpu without HT is retarded.

its almost as bad as disabling all 7 cores and leave one core running on an i7
 
lol I also leave it enabled because I just love seeing 8 "cores" in my windows task manager =)
 
jonneymendoza said:
imo using a i7 cpu without HT is retarded.

its almost as bad as disabling all 7 cores and leave one core running on an i7
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Your statement is... well...

If user x never uses anything that will take advantage of 8 threads, why leave HT on, when it lowers your OC and increases heat?

And because it's an i7, it will run faster clock-for-clock than a Qxxx anyway. And most 920's get to 4.2GHz with HT off on air pretty easily, while most Qxxx's don't even get to 4.0GHz..

What's the issue?
 
Brahmzy said:
Your statement is... well...

If user x never uses anything that will take advantage of 8 threads, why leave HT on, when it lowers your OC and increases heat?
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Would the same logic apply to user x that only uses 2 cores of their quad core processor?
 
Brahmzy said:
Your statement is... well...

If user x never uses anything that will take advantage of 8 threads, why leave HT on, when it lowers your OC and increases heat?

And because it's an i7, it will run faster clock-for-clock than a Qxxx anyway. And most 920's get to 4.2GHz with HT off on air pretty easily, while most Qxxx's don't even get to 4.0GHz..

What's the issue?
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Your statement is "... well..." too and you don't even notice it. You forget that you and everyone else are not running just ONE single-threaded program at any given time, so HT is useful NOW for multi-tasking and as multi-threaded programs become prevalent, it'll be even more so as time passes.
 
Regardless of oc potential, I think that peoples fail to realize that HT has actually a negative performance impact on many applications. It is true that some apps benefit from HT (x264, Cinebench) but most users would be better off with HT disabled.
 
yeah, that negative performance impact is completely overblown out of proportion, and most users won't see any benefit from turning off HT in a single program but will definitely see the difference in multi-tasking capabilities.
 
Brahmzy said:
, while most Qxxx's don't even get to 4.0GHz..
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Most can like, Q6600 G0, Q9450, Q9550, Q9650 and all the QX**** can do 4Ghz or higher. FYI

/offtopic.

I keep HT on but I will turn it off since I want to get higher but I also need a new waterblock so I dont have to use zip ties to hold my dtek in place. :eek:
 
I used to think it was dumb to turn off HT.

Now I'm running 4.2Ghz with turbo mode, HT off, load temps mid to upper 80s in real temp 3.0 while running linx. I also noticed some programs run way, way faster with HT disabled.

I've turned into a believer of HT off. I guess more threads are not always better. I saw frame rates in second life jump from mid teens to upper 30s to upper 40s, just by disabling HT and going from 3.92Ghz to 4.2Ghz.
 
Brahmzy said:
Your statement is... well...

If user x never uses anything that will take advantage of 8 threads, why leave HT on, when it lowers your OC and increases heat?

And because it's an i7, it will run faster clock-for-clock than a Qxxx anyway. And most 920's get to 4.2GHz with HT off on air pretty easily, while most Qxxx's don't even get to 4.0GHz..

What's the issue?
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i diddnt say it was an issue. i just said its a bit retarded to do so. But its your CPU so you can do whatever you want with it, disable 7 cores for all i care.
 
RadXge said:
http://ixbtlabs.com/articles3/cpu/ci7-turbo-ht-p1.html

This makes a good argument for disabling HT.
Enabling HT because it is there... is not very convincing!
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I hope you all didnt miss this. Take a good look at those gaming benchmarks. It depends what you use the i7 for of course, HT does benefit some apps.

Lets not pretend that the i7 has eight cores. It has four. HT works by faking a second full processor, but there is only 1 execution unit per real core. (oversimplifying, but you get the idea).

This is the best write-up I've found explaining the pros/cons, yes its dated but HT info hasnt really changed for i7: http://www.novell.com/coolsolutions/feature/637.html. The tl;dr:

that article by Novell said:
# Resources such as cache, the floating point unit, etc, are shared - so if these parts of the processor are being heavily utilised by one process (on one of the virtual CPUs) then the other process (on the other virtual CPU) may not get its fair share of these shared resources

Hyper-Threading will increase the latency of individual requests and trade that for increased throughput; any individual request takes longer to complete, but more requests can be completed in a given time period. Going from uni-processor to multi-processor also adds cache contention and the increased locking complexity also slows things down; so performance will vary depending on what you are doing. You end up with two virtual processors running at around 65% the speed of a stand-alone processor. If you add the two together you get 130%.

Therefore, if the workload doesn't max out a uniprocessor system, you wouldn't want to add latency to each individual request (i.e. by turning on Hyper-Threading) just so you can increase the throughput - because your current throughput capacity is more than sufficient for the workload. Hyper-Threading should be used to increase throughput in servers that are maxed out.
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And with the i7, "if the workload doesn't max out a uniprocessor system" becomes "if the workload doesnt max out a quad processor system".
 
i thought this had been settled thru testing? there being a few very specific apps that benefitted from ht on, all the rest did not. so if you dont run those apps........
 
and if you want better h.264 encoding - use cuda or avivo - light years faster than any cpu.
 
and I get way to many points off in separate threads - Okay look. There ARE apps that will benefit from HT on an I7. I won't deny that. But those apps are few and far between and very specialized. So much so that probably 99% of us don't use them. If you do, great, awesome - you probably make some sort of living at it since those apps are very very expensive...and in those situations you are probably not risking your end results on an overclocked cpu.

The argument "why get an i7 to turn HT off.." is just stupid. If all i7 gives is HT then yah why get it? that is not all you get. On chip memory controller anyone? - This is [H]ardOCP. We are geeks who buy parts and oc the hell out of them for fun. I have a Q6600 system I never overclock - you know why? I need it to be up 24/7 and not crash so I don't mess with anything that can cause stability issues and run it at spec. You know what - it never has crashed...you want stability don't OC your system plain and simple.
 
i wouldnt ever dream of turning off ht.
first of all, its one of the coolest things ever to have 8 virtual cores. i would kill for that.
second, how stable can a pc be if you had to turn off ht to have a usable computer.
third, although the ht gains can be small to none, the clockspeed differences between the ht on and ht off overclocks also is very small.
and dx11 games will be fully multithreaded, so dont get too used to leaving ht off ppl.
 
grimreeferx09 said:
i wouldnt ever dream of turning off ht.
first of all, its one of the coolest things ever to have 8 virtual cores. i would kill for that.
second, how stable can a pc be if you had to turn off ht to have a usable computer.
third, although the ht gains can be small to none, the clockspeed differences between the ht on and ht off overclocks also is very small.
and dx11 games will be fully multithreaded, so dont get too used to leaving ht off ppl.
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there is a huge difference between being a multithreaded and optimized for 8 cores. Game makers have to build to the lower common demominator. So until most systems out there are multicore - your probably not going to see anything that is optimized for 4 let alone 8 cores.

To the other poster - the system is not unstable until you turn ht off it just hinders max OC. If my max oc is 3.6 with HT on and 4.0 with HT off - then I can bet you 100 bucks that in the system will perform faster at 4 physical cores at 4.0 ghz than at 3.6 and 8 virtual cores.

the point is - if your trying to get a max OC and temps are an issue - try turning off HT. It does nothing, and affects your OC. If you can run HT at your MAX oc great! awsome leave it on.
 
groebuck said:
and if you want better h.264 encoding - use cuda or avivo - light years faster than any cpu.
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Faster yes...better NO!
It's craptastic encoding "quality" only good for downgrading movie to a lower, more crappy resolution.
 
TehQuick said:
Your statement is "... well..." too and you don't even notice it. You forget that you and everyone else are not running just ONE single-threaded program at any given time, so HT is useful NOW for multi-tasking and as multi-threaded programs become prevalent, it'll be even more so as time passes.
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You don't even freaking OWN an i7, do you? - so you're talking out of your ass on this. I DO, and I'm running HT for ONE program, because it uses all 8 threads. If it wasn't for that ONE program, I'd disable HT and still have 4 usable cores. The "multitasking" you're talking about may not even benefit from virtual cores, and the casual user typically won't be doing any multitasking past what 4 cores can handle. Discussing what may come in the future is "retarded" because it ain't what's in the future that's important, it's what USER X is doing NOW, TODAY. If the user needs to use a program that will take advantage of 8 threads, then by all means turn HT back on.
 
fully loaded, there isn't a lot of heat difference between HT and non-HT settings [edit: i observed 1C for the record]. however most real apps don't fully load the cpu, so i don't know about that usage pattern.

Linux kernel compile is much faster with HT on. But maybe Linux handles the scheduling better than Windows.
 
I call BS on the whole HT makes your CPU 10C hotter. Now the overclocking issues, I can see, the heat issues are what I'm calling BS on. Whether overclocked or stock, HT on or off, idle temps are the same. Load temps show a small difference, more like 2C at stock and 5C overclocked. 10C difference would have to be an EXTREME overclock.
 
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