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!! 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! 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.