5 Replies Latest reply on Feb 4, 2015 11:06 AM by joe_intel

    i7 4790 not reaching full turbo


      My i7 4790 is not reaching the full turbo boost, it is stuck at 3.8ghz while it supposed to work at 4.0ghz. Why?


      I know that the turbo it's not supposed to work at full clock all the time. But he does not reach that any moment.


      Mobo: Asrock z87 pro4 (last bios version)




      btw i'm not using the stock cooler.

        • 1. Re: i7 4790 not reaching full turbo

          Intel® Turbo Boost engages automatically and depends on the processor’s temperature, voltage, power, load, and the number of cores being used. We suggest making sure this feature is enabled in BIOS or contacting the motherboard/system manufacturer.

          • 2. Re: i7 4790 not reaching full turbo


            I have exactly the same issue like skraftnm. My system is the following:

            Motherboard: Asus Maximus VI Hero; BIOS version 1603 (latest version)

            Processor: i7-4790

            Memory : HX321C11T2K2/16; Kingston HyperX 16GB DDR3 Kit

            • JEDEC: DDR3-1600 CL11-11-11 @1.5V

            • XMP Profile #1: DDR3-2133 CL11-12-12 @1.6V

            • XMP Profile #2: DDR3-1600 CL9-9-9 @1.6V

            Graphic Card: None. I use the one built in the CPU for now.

            Monitor: HP LP1965

            Storage #1: Samsung 850 Pro 256 GB SSD

            Storage #2: Seagate 500GB 7200 HDD

            CPU Cooler: CM Hyper 212 EVO

            Case: CM HAF 922

            Power Supply: CM Silent Pro M700

            OS: Windows 7 Ultimate 64 bit

            In BIOS I have turbo boost enabled, core ratio is on Auto. If I try to change manually the core ratio to anything higher then 38 in goes back to 38. Bus speed is 100 by default. I have got the feeling that max turbo frequency of this CPU is locked to 3.8 GHz Can someone from Intel confirms that this CPU is capable of reaching 4.0 Ghz or 3.8 is its maximum?

            • 3. Re: i7 4790 not reaching full turbo

              Please make sure all cores are enabled in BIOS. In Windows* System Configuration utility (msconfig) we suggest leaving the Boot Advanced Options as default, so Number of processors should be left unchecked.

              You may also consider updating the BIOS.

              • 4. Re: i7 4790 not reaching full turbo

                Thanks for the reply joe_intel. After some trial and error I found that setting in BIOS - AI overclock tuner from XPM to Auto solved the problem. Now my multiplier is 8-40. and I can see some cores reaching 4.0 GHz. If I understood correctly from the CPU specification if 1 or 2 cores are actively working they can reach 4.0 GHz, with 3 working cores frequency is locked to 3.9 GHz and with all four working frequency is up to 3.8 GHz. Is that correct?

                • 5. Re: i7 4790 not reaching full turbo

                  You are getting the idea behind it; nevertheless, such values may not be necessarily correct.

                  Page 45 of the datasheet provides more details: https://www-ssl.intel.com/content/www/us/en/processors/core/4th-gen-core-family-desktop-vol-1-datasheet.html