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Intel fan mod. 775, i5, i7

Discussion in 'General Hardware' started by Lazzer408, Oct 12, 2009.

  1. Lazzer408

    Lazzer408

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    I don't know if it's ever been pointed out before. I have yet to see this mod.

    The factory Intel (775, i5, i7) coolers have a thermistor on-board that restricts the maximum RPM the fan will do. Under normal circumstances it's measuring the internal case air temps flowing over the fan. If the internal air temp is high then the fan is cooling the cpu with warm air. It will increase the RPM to compensate. This adjustment is completely independant of the PWM signal from the motherboard!! :eek: So your BIOS could sense the CPU at 70+ and be telling the fan "more more more" but if the fan isn't sucking in hot air then it won't actually do what it's capable of! :eek:

    Removing the resistor allows the fan to run FULL SPEED. I would guess is probably twice what it normally does judging by the sound and airflow. This mod only effects the maximum speed of the fan. The BIOS will still have PWM control of the fan's minimum speed and can still slow it down. For example. If the RPM was 750-1500 it will now be 750-3000. I don't have an i7 CPU to load test for temps. If someone else has an i7 and wouldn't mind doing some tests that would be great. The i7 thermistor is a bit harder to get at but just put a small amount of solder on the tip and the resistor should stick to it for removal. Or just pluck it off with a screwdriver.

    The results are...
    Note the effect the increase in cooler air has on the NB.

    Test setup:
    -E6750 2.66 @ 3.0
    -Stock Intel HSF. Both the small (same as e5200) and the larger (q6600)
    -CPU fan set to max performance (BIOS)
    -Benchtop testing (out of case)
    -With resistor max RPM = 1980
    -Without resistor max RPM = 3240

    Unmodded idle.
    -CPU 32c
    -MCP 44c

    Modded idle.
    -CPU 28c (small) / 24c (large)
    -MCP 35c

    Unmodded Prime95
    -CPU 60c

    Modded Prime95
    -CPU 54c (small) / 49c (large)

    Well there you have it. It's worth 4c idle and 6c under load. Great news for people that just want a little better cooling out of the stock heatsink for whatever reason. Maybe a HTPC build, space, or cost is a limiting factor for a heatsink/fan upgrade. This could be a great help to you. The difference may be higher with the larger Intel HSF. I will test the larger Intel HSF in a moment but it's already modded. I can't give you before/after results with it. Unmodded the temps were almost the same as the small one iirc. I used the small one because this is a mini-ITX build and performance was almost equal so I saved some space. The larger Intel HSF (modded) does a good job of keeping a slightly overclocked E-series c2d just under 50c. This could be due to the contact area of the copper to the CPU. The small HSF has a contact diameter of 22mm and the large HSF has a contact diameter of 28.5mm. I should also note that I felt the fan's motor after running it full speed for some time and could hardly tell it had been running at all.

    Here are pics of the mini, large, and i7 HSFs.

    [​IMG]
    [​IMG]
    [​IMG]
     

    Attached Files:

    Last edited: Oct 12, 2009
    angelkiller, erocker, FilipM and 4 others say thanks.
  2. Exeodus

    Exeodus

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    Very interesting, keep us posted.
     
  3. Lazzer408

    Lazzer408

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    I'll be posting both 775 and i7 results. It's cooking now. :D
     
    Last edited: Oct 12, 2009
  4. Chicken Patty

    Chicken Patty WCG Moderator Staff Member

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    looking forward to the results :toast:


    Thanks for sharing
     
  5. Solaris17

    Solaris17 Creator Solaris Utility DVD

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    dude awsome this will totally help those that want to crunch as their temps will be lower same with those that do but stop cause of heat..and those that cant afford a diff cooler...


    AS WELL

    as people who want to game and wory about temps or have overheat issues during the summer cause of crysis.
     
  6. Mussels

    Mussels Moderprator Staff Member

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    curious.
     
  7. Duxx Guest

    Always good to know :D I would use my stock i7.. but its back at home. doh!
     
  8. Maban

    Maban

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    I have an E5200's fan and I'm not seeing a thermistor like you have in the OP.
     
  9. Lazzer408

    Lazzer408

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    Oh? Did you check the spoke that the wires are on? Maybe there was a change in design somewhere along the way.
     
  10. Maban

    Maban

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    Nothing juts out of the PCB. Its all round. The fan is an E33681-001. PCB was made 16th week of 2009. Full 12V is 1757-1834RPM in bios.
     
  11. Lazzer408

    Lazzer408

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    This is model E30307-001 and actually came with a Q9550 but was physically the same as my E5200 so I assumed it's the same cooler. I stated E5200 for reference to the size. Someone might think a quad-core would come with the larger HSF. Sorry for any confusion. If you want, power it up off a 12v supply (without the tach or pwm wires connected) and take a hairdrier to it. See if it speeds up. If it does then it has that thermistor somewhere unseen. I'm not sure it's worth the trouble if taking it apart to remove it though.
     
  12. overclocking101

    overclocking101

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    mine has a thermistor on it, what do you do to mod it? just take the resistor off? how is this mod done?
     
  13. KainXS

    KainXS

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    can you OC more now that you get better temps with that.
     
  14. Lazzer408

    Lazzer408

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    :D
     
    Last edited: Oct 13, 2009
  15. Hayder_Master

    Hayder_Master

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    very nice work dude keep on update and im go try it too
     
  16. Lazzer408

    Lazzer408

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    Yes I was able to squeeze a little more out of my CPU and still maintain my thermal goal of <60c.
     

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