Why oh why does HT need to be off?

[DdotRoq]

Hello Everyone,

I was overclocking a bit yesterday and learned the following:

overclocked to 4.0 ghz - HT on - somewhat stable somewhat unstable - idle temps of 40 degrees C with Load temps of 75 degrees C.

overclocked to 4.1 ghz - HT OFF - fully stable - idle temps of 30 degrees C with Load temps of 65 degrees C.

What gives? I'd like to leave HT on as I am convinced "If it is there, then it must be good"...

I'm also still wondering if I am able to make it to 4.6...

[OverDozeD]

HT on makes chip much hotter than HT off and need way more vcore

[DdotRoq]

HT on makes chip much hotter than HT off and need way more vcore

Correct, I've personally experienced this, but isn't HT a nice feature to have on?

Also, how do I play with the QPI to achieve higher overclocks, ie. 4.6 or so...

[dexster]

i would say most people would have ht on for everyday use
ht off for cpu/ram testing or benching etc

edit:- also for gaming ht is best turned off ...in vista anyway

[OverDozeD]

but isn't HT a nice feature to have on?

Actually why not?
Depends on what you want to bench
for 24/7 I use 200x20 HT off
my 920 has horrible 1.29 VID and TRUE120 doesn't allow me to OC more

[v0dka]

There's no way you are going to get 4.6Ghz stable on water, even with HT off. I do recommend not using it since there's now way you will be using 8 threads unless you crunch.

[DdotRoq]

There's no way you are going to get 4.6Ghz stable on water, even with HT off. I do recommend not using it since there's now way you will be using 8 threads unless you crunch.

If a 965 can do it, why can't I?

And your at 4.4 on a Core 2 Duo, I am on a Core i7 940... I am assuming you are WC'd, unless you achieved those marks under LN2 or DICE.

[Xello]

4.6ghz will require more volts than a 24/7 setup should be running, you're into benching territory there. i7 doesn't really overclock much higher than the latest generation core 2 chips, 4.2-4.4ghz is the normal max for 24/7 use on both brands.

HT enables you to use 8 threads. If you are using programs that will use all 8 threads then it's beneficial, if you're not then it's holding your overclock back, it's as simple as that.

[v0dka]

If a 965 can do it, why can't I?

And your at 4.4 on a Core 2 Duo, I am on a Core i7 940... I am assuming you are WC'd, unless you achieved those marks under LN2 or DICE.

Where does a 965 do 4.6Ghz stable 24/7 without phase?

Even if you manage to find one, chances are very slim that you can do the same. My result is on air btw. And it's an E0 Wolfdale, which easily does the highest freqencies of the whole Intel lineup.

[Rammsteiner]

If a 965 can do it, why can't I?

And your at 4.4 on a Core 2 Duo, I am on a Core i7 940... I am assuming you are WC'd, unless you achieved those marks under LN2 or DICE.

lol, not a lot 965's clock high tbh. That's why I love my 920 since it's a pretty nice clocker, but some people cant even get past 3.8Ghz, no matter if you've a 965, 940 or 920.

If you're looking for a 24/7 OC but cant really get further, be happy anyway. In the end you've a faster system than you can buy in the first place

[DdotRoq]

lol, not a lot 965's clock high tbh. That's why I love my 920 since it's a pretty nice clocker, but some people cant even get past 3.8Ghz, no matter if you've a 965, 940 or 920.

If you're looking for a 24/7 OC but cant really get further, be happy anyway. In the end you've a faster system than you can buy in the first place

I'd like to get to 4.2 AND stable with HT on... it appears I might only be able to reach there with HT off, if that. :-/

I take it you have your CPU @ 21x?

[bahlgren342]

I'd like to get to 4.2 AND stable with HT on... it appears I might only be able to reach there with HT off, if that. :-/

I take it you have your CPU @ 21x?

I couldn't get over 3.8 with HT on unless I bumped the vcore and VTT considerably. and it ran HOT with my TRUE. 4.2 should be reachable on WC with HT on.

Currently at 200x20(21) with HT at 1.35v @ load. (1.3v bios)

highest core Idle temp is 45. Max load ~67. (are high idle temps normal for AS5?)

Also, unless crunching HT doesn't really add much performance. I've read that it's not even that much better for encoding, etc.

I game so I keep it off, but I wish I could have it on too to crunch. =/

[ewitte]

If I can control the temperatures I can get 4.3Ghz working at 1.3-1.325v stable I'm sure 4.6Ghz is possible on water and it wouldn't crash but I wouldn't want to run my vcore that high 24/7 IMO. Shooting for 4.2Ghz 24/7 when the water is on.

Right now 4.3Ghz and HT on gets hot really quick. Pit test at 4267 but that only does multi core for about 2.5s. Only doable because I had 1000-2000CFM blowing at the MB.

http://www.pcpitstop.com/betapit/sec.asp?conid=21868521 - 20474

[bahlgren342]

You must have a good batch because most people cant get over 3.8 with HT on without raising the vcore up to 1.4v+ or passed 4.2 without raising it to 1.4v+.

[Falkentyne]

Threads use more transistors on the CPU.
Those things give off heat as your CPU has to work harder, and put more stress on the components.
Therefore, you can't overclock as far with HT on.

It's similar as to how 64 bit windows or 64 bit linpack/prime is harder on an overclock than 32 bit versions; less parts of the CPU are being used compared to more for 64 bit.

Only time will tell if new steppings will eventually start hitting 4.5 ghz on air with HT on at decent voltages.

And unless you're using one of the what, 2 or 3 games on the market, that will use 8 threads (and you better be using triple/quad SLI with that) or are doing professional rendering work (or crunching), why do you need 8 threads anyway? Finding a use for 4 is hard enough except for a small segment of users.

Oh and just like in the Pentium 4 days, HT on can actually HURT performance in some applications, if the application isn't coded to handle multiple threads ("virtual" cores) properly rather than physical cores, and there are a number of those apps out there.

[TinTin]

I doubt how many users disable HT running at 200X20? for 24/7 usage
Enabling HT at such clock, producing much more heat and need rather lot of Vcore to stablise the HT.

I am not asking people to disable it, just want to know how many?

[bahlgren342]

I doubt how many users disable HT running at 200X20? for 24/7 usage
Enabling HT at such clock, producing much more heat and need rather lot of Vcore to stablise the HT.

I am not asking people to disable it, just want to know how many?

I disable mine, I'm a gamer primarily so I want a nice high clock with low temps.

I don't think there are any games that utilize more than 4 cores is there? Pretty sure all games so far are 4 core max support.

Although I wish I had HT on sometimes for crunching. Long ways for me to catch up to the big guns in crunching.