CPU: Intel Core i5 3470 3.20GHz box
Video card: Gigabyte Radeon HD7950 WindForce 3X 3GB DDR5 384-bit
Storage: SSD Intel 120GB SATA-III 330 Series 2.5 inch 9.5 mm
Western Digital 1TB SATA-III 7200 rpm 64MB Caviar Blue
Motherboard: Gigabyte GA-B75-D3V
Memory: Corsair XMS3 8GB DDR3 1600MHz CL9 Dual channel kit
PSU: OCZ ZS Series 550W
Case: Aerocool Strike-X GT
Using the box CPU cooler. Found the following issue: when powering up the PC the CPU cooler doesn't start immediately, it goes through 2 impulses before it actually starts. What I mean about this is, there are 2 small impulses, 1-2 seconds away from each other, where it seems to try to start but it doesn't move a single step ( these are stepper motors ? ). The behavior is consistent with each power up I am doing.
Tried a different cooler on the above configuration, it works normally. Tried the suspicious cooler on a different configuration, it behaves the same.
Is this normal?
More about :intel box cpu cooler perculiar behavior
The heatsink fan is temperature controlled by the motherboard. When you first boot your computer the processor is cold, the motherboard might attempt to spin the fan at a slow speed to reflect this. All that has happened is that the setting was so low it failed to start the fan until it could overcome the initial resistance of the fan. It's normal.
I don't know if it has changed but AMD systems spin the fan at 100% then slow the fan down upon cold boot.
Here are some extra details that might change your opinion:
I tested the box cooler on an older system, Asus P5P800 motherboard and Intel P4 2800Mhz CPU - LGA775. I used the P4 box cooler for 4 years before I changed it with an aftermarket, Akasa cooler. Both of these ran instantly when powering up the old and the new PC.
The box cooler from the I5 had the strange behavior on both platforms.
I'll add to what I said and make a small ammendment.
There are a large variety of heatsinks and fans. The load the fans need to startup varies across the board, this means that while some fans start spinning others may twitch. It's also worth noting that a few years ago we switched from a 3-pin to a 4-pin fan header which allows for a greater degree of fan control, not just aat the mid speeds but at the low and high speeds. Lastly, motherboards deal with fan speeds in thier own way until it's had a chance to boot, some spin slow, others spin fast.
It's a combination of these slow motherboards with fans that need high startup loads that causing your fan twitches. But as long as your processor doesn't overheat, you're fine.