Do i really need hyper threading on?

[LiamHUD]

I have a Intel Core i7 4790K but i'm not overclocking. My temps while playing CPU heavy games like Battlefield 1 are bouncing from 55-59 degrees celsius. If i turn hyper threading off what are the pros and cons? I'm really looking for it to cool my CPU even more but still have the same performance (am i right saying that)

Thanks

 

[JackNaylorPE]

1. There is no reason to try to cool a CPU any "more" when it's running w/ tempos in the 50s.

2. Turning HT off, will lower temps because you will only be using half as many core; with the 2600k, this was up 7C when OC'd o the max, at stock levels impact was minimal.

3. In gaming, while there is a small difference, you won't be able to notice it.

4. In applications that use HT, you will notice... for example video editing is significantly impacted

 

[USAFRet]

55-59C under load, you don't need to do anything.

Lowering that temp a little bit (at most) brings no further performance increase.
Turning off parts of the CPU functionality does bring a performance hit with many applications.

Just leave it.

 

[TMTOWTSAC]

60 C isn't at all bad for a 4790k under load. And I believe with HT off it would still be using 4 cores. It would just run 1 thread per core rather than 2, as opposed to 2 cores each with 2 threads. As far as performance, some games (for example, Battlefield 1) absolutely take advantage of HT. You can see it in the benchmarks comparing i5's (4 cores) to i7's (4 cores, 8 threads.)

 

[thx1138v2]

IMO, it's just a personal preference. I live in a place where it gets hot and stays hot all through the summer. Pumping heat from my machine into the room somewhat causes my air conditioning to run more so it's more important to me to keep machine temps down during that time. The air conditioning is the major component of my electricity bill in the hot months.

As far as game play goes, it's going to depend on the specific game because some are good at taking advantage of multiple threads, BF1 being one of those, and some aren't. You can generally judge the performance difference by frame rates but your subjective perception and tolerance for lower frame rates is probably more important.

Different people have different perceptions of frame rates. It's kind of like "beauty is in the eye of the beholder" which is literally true because everyone has a different perception of what they are seeing. Sight occurs in the eye but vision occurs in the brain because that's where what is seen is processed.

So I'd say try it both ways for a week or two and see if there's any perceptible difference that justifies the hyper-threading.

http://www.pcgamer.com/how-many-frames-per-second-can-the-human-eye-really-see/

 

[geofelt]

If you have a "K", you should be planning on at least a modest overclock.
With a minimal tower type air cooler and a 120mm fan, you should have no issue with temperatures.
The key is to keep vcore at a safe level, that is about 1.3v.
It is vcore that drives up the temperature.
Under heavy load, I might guess 70c., a stress test might be 80c. Either will be OK.
The chip will slow down or turn itself off if it reaches a dangerous level which is about 100c.

As to hyperthreading, keep it on.
I know few games will use more than 2-3 threads.
I thought there might be a problem if a critical task got stuck being dispatched on a hyperthread, and there might be some benefit from turning hyperthreading off.
It turns out that is not the way it works.
Each thread is potentially capable of full speed utilization.

 

[JackNaylorPE]

IMO, it's just a personal preference. I live in a place where it gets hot and stays hot all through the summer. Pumping heat from my machine into the room somewhat causes my air conditioning to run more so it's more important to me to keep machine temps down during that time. The air conditioning is the major component of my electricity bill in the hot months.

Rest assured that turning HT off will not affect your electricity bill in any measurable way.

The TDP for the 4790k is 88 watts
The TDP for the 4790 is 84 watts

Assuming you were using the PC at full power 30 hours a week

4 watts x 30 hours x $0.13 avg US electric cost / 1000 watts per kw = 1.3 cents per month


I have not as yet observed any difference in game play with HT off except under the following conditions:

a) OC is temperature limited ... a better cooler would eliminate this.
b) Turning off HT, may get you 5-7C lower temps allowing a slight boost in OC.
c) Benchies will show slightly higher fps but its small enough that your eyes won't know the difference.

As for more threads, it's easy to see if the extra threads are doing anything for you.... as of yet I have not been able to show any increase performance with > 4 threads in th games I have played. here's how:

a) Start your Game
b) Go to Windows task manager, processes tab and right click on the exe file
c) Set affinity 1 Processor
d) Run a demo or bench or go thru a certain segment
e) Record FPS
f) "Rinse and Repeat"assigning 2 processor, then 3 and so on thru 8

I have yet to see any increase after 3 processors.... again, on the games I have played. Your results may vary based upon playing resolution, RAM, GFX card(s), etc

If you never see a benefit w/ 5 or more processors, HT is doing squat for you.