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Why is my i5-4590 showing 100% use with prime95 but runs at 128 F and uses 42 watts?

THiat
Beginner
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It's in a Dell. The ms/iteration times are around 39-45 which is slower than my i5-2400 at 21-25 ms/iter. Memory is DDR3-1600, 4 G. Using two different hardware monitors, the only difference I can see is the i5-4590 is running at 42 watts and the i5-2400 is at 83 watts, and 165 F. Speed step off/on, turbo boost off/on, no difference. Dell has replaced the motherboard, no difference. Any ideas?

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THiat
Beginner
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Ok, more information: I downloaded Intel Extreme Tuning Utility, and it reports TurboBoost is disabled. In the bios, it's still enabled, and Win 7 power settings are set to High Performance. In the past, there was a TurboBoost driver for Windows, but I don't see one now. Any other settings might cause this?

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Jose_H_Intel1
Employee
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In regards of Intel® Turbo Boost Technology, is Intel® SpeedStep™ Technology enabled?

Did you update the system BIOS?

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THiat
Beginner
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Yes, I updated the BIOS (easy to do with Dell), and in that BIOS, multicore support is set to All, SpeedStep is disabled, C states is disabled, CPUID limit is disabled, and Turbo Boost is enabled. I have tried it with SpeedStep enabled also, no difference.

Attached is a screen shot of Intel XTU:

This screen grab is with Prime95 running on all four cores. Is there a Windows 7 setting that could turn off Turbo Boost?

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Jose_H_Intel1
Employee
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Please make sure that "Number of processors" is unchecked in the Boot Advance Options of Windows* System Configuration Utility (msconfig ). You may want to reset the BIOS settings back to default (but pay attention to your SATA controller and boot settings in case they need to be modified).

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THiat
Beginner
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Thanks for helping me with this.

"Number of processors" was unchecked in the Boot Advance Options of Windows System Configuration Utility.

I reset the BIOS to factory settings, and I noticed no difference in performance. However, the Intel Extreme Tuning Utility now shows Turbo Boost as enabled, but the performance figures are the same for normal mode of Prime95.

I tried Torture Test mode on Prime95, the mode that makes maximum CPU heat. The watts came up slightly to 63, the frequency was still unchanged, and the temps came up to 154 F with no thermal throttling. See the screen grab.

Under full load, shouldn't the watts be 80+ and the temps be 165F+ with a stock heat sink/fan with the fan speeding up? No fan speed up yet.

 

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Jose_H_Intel1
Employee
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The temperature should not be a concern

Did you try updating the system BIOS?

What memory clock speed and voltage settings are you using?

Can you run the Intel® Processor Diagnostic Tool?

http://www.intel.com/support/processors/sb/CS-031726.htm Processors — What is the Intel® Processor Diagnostic Tool?

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THiat
Beginner
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I downloaded and ran the Intel Processor Diagnostic Tool, it passed all tests except Front Side Bus Test and QPI Test which were both Unsupported.

I updated the system BIOS to the latest.

CPU and memory clock speed and voltages from CPU-Z. Does anything look wrong?

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Jose_H_Intel1
Employee
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Are you able to see the CPU clock frequency going higher than 3.3 GHz in CPU-Z with Intel® Turbo Boost and Intel® SpeedStep™ Technology enabled while the Intel® XTU stress test is running?

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THiat
Beginner
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Yes, the frequency does go higher with Intel® Turbo Boost and Intel® SpeedStep™ Technology enabled. I notice that at idle the processor frequency is 3.692 Ghz. When I turn on Prime95, the processor frequency drops to 3.29 Ghz. When I stop it, the processor frequency rises to 3.692 Ghz. Shouldn't it stay high under full load? You can see that the temps are not excessive and there is no thermal throttling. And the CPU Total TDP doesn't go above 45 watts, when under full load it should be 80+ watts. Under Intel XTU CPU stress test, the frequency also drops to 3.46 Ghz and the watts range between 45 and 49, with the temperatures between 129 and 135 F. Here's a screen grab from Intel XTU of turning Prime95 off and on:

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THiat
Beginner
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Another piece of the puzzle: under Intel XTU, with full load, it shows Current Limit Throttling at 100%. With no load, it shows 0%. Doesn't Current Limit Throttling occur when the motherboard is sending current above specifications?

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THiat
Beginner
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Final report on this thread:

Was not able to address the current limit throttling. Dell sent a replacement motherboard, then a replacement computer, no difference. To Dell's credit, they are going to RMA the computer and refund, even though it was sold by a third party, antonline.com through newegg. Excellent customer service from Dell, though.

It looks to me like the current limit throttling from the motherboard was designed by Dell to not run the CPU too hard to prevent wear/failure and prevent Dell service calls.

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