[SOLVED] Why can't my CPU work at 100%

[Shanks_1]

I got a i5-4460 and base clock is 3.20 but with boost should go to 3.4 which never reaches even under stress, same thing goes for the CPU load it won't hold at 100% even if the task requires it to run at 100%. Any reasons why it behaves like this?

 

[rgd1101]

What task that should run at 100%? what the temp?

 

[mdd1963]

RUn HWMonitor, then launch Prime95....

At least one core should boost to advertised clock speed....

Temps with latest P95 (default blended) will likely hit ~75-80 C in 2 minutes, depending on cooler

(Be sure to 'STOP' P95 when satisfied with load behavior, as merely closing the app leaves it still running full throttle in background...)

 

[Karadjgne]

Run CPU-Z.
Then run Prime95 v26.6 small fft. That'll put the cpu at 100% load consistent. Blend and Large fft do not. Versions after 26.6 use AVX, which that cpu has no way to turn off and will put temps through the roof.

In CPU-Z, if you look to the left side it'll show in MHz just what the cpu is now running at. It should be 3397MHz or very close, which is 3.4GHz. The BCLK should be 100 but can read 99.98 on some mobo's.

If it's not running at boosted speed there, then you have a limiter on the cpu somewhere.

There's actually very few programs that'll drive a cpu to a 100% consistent load, even stress/temp tests like Intel burn-in or aida64 bounce between @ 80-100% usage.

 

[Shanks_1]

What task that should run at 100%? what the temp?

i belive is decompressing of some sort a large file and temps are aroudn 50-60. (sorry the late reply)

 

[Shanks_1]

RUn HWMonitor, then launch Prime95....

At least one core should boost to advertised clock speed....

Temps with latest P95 (default blended) will likely hit ~75-80 C in 2 minutes, depending on cooler

(Be sure to 'STOP' P95 when satisfied with load behavior, as merely closing the app leaves it still running full throttle in background...)

(sorry the late, i did as you said and the max spped was 3.19ghz even tho in the bios i have enabled turbo boost)

 

[Shanks_1]

Run CPU-Z.
Then run Prime95 v26.6 small fft. That'll put the cpu at 100% load consistent. Blend and Large fft do not. Versions after 26.6 use AVX, which that cpu has no way to turn off and will put temps through the roof.

In CPU-Z, if you look to the left side it'll show in MHz just what the cpu is now running at. It should be 3397MHz or very close, which is 3.4GHz. The BCLK should be 100 but can read 99.98 on some mobo's.

If it's not running at boosted speed there, then you have a limiter on the cpu somewhere.

There's actually very few programs that'll drive a cpu to a 100% consistent load, even stress/temp tests like Intel burn-in or aida64 bounce between @ 80-100% usage.

Thanks for the explation of the reason why it wont stay at 100% load on certain task i did as you said the core speed does not go any higher than 3192 even tho i have turbo boost enabled in the bios.

 

[Dragos Manea]

Turbo boost is for a single core, if you need to use all cores it will revert to base frequency, you misunderstood what turbo boost is.

 

[Shanks_1]

Turbo boost is for a single core, if you need to use all cores it will revert to base frequency, you misunderstood what turbo boost is.

my cpu z shows 3192 which core is that? and does that single core makes a differnce if it goes to 3.4?
Could you explain how turbo boost works please.
i ran prime95 and was 100% use with 3192 fix frequency.

 

[rgd1101]

http://www.cpu-world.com/CPUs/Core_i5/Intel-Core i5-4460.html
Maximum turbo frequency 3200 MHz (4 cores)
3300 MHz (3 cores)
3400 MHz (1 or 2 cores)

 

[Shanks_1]

http://www.cpu-world.com/CPUs/Core_i5/Intel-Core i5-4460.html
Maximum turbo frequency 3200 MHz (4 cores)
3300 MHz (3 cores)
3400 MHz (1 or 2 cores)

when i run prime95 and check on cpuz then it shows me the 4 core one right?

 

[Karadjgne]

In Prime95 you can run 1x, 2x, 3x or all 4x workers, so you can see what your speeds are for 1, 2, 3 or 4 cores.

3.192GHz is 3.2GHz rounded as there can be a % difference due to other timings like BCLK not at a pure 100.00 because of loss in circuitry.