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I've never bothered to test my fans in pull-only mode, but tonight I accidentally attached my San Ace 9S1212H401 fan backwards: it was facing me rather than the Megahalems.
It was a few minutes before I noticed that the fan was sucking air rather than pushing air through the stack. So I let OCCT finish the run. An hour later, I learned that the fan, pulling air, had achieved a difference of 48.5c over ambient.
The rig is my sig rig, running at Vcore 1.28v, 4004MHz with a Vtt=1.19v, PCH=1.2V, PLL=1.9V and DRAM=1.616v. The 48.4c diff is not bad. The best I've gotten so far is with twin Ultra Kaze 3000's, at 44.5c difference, and with twin San Ace PWM fans running nearly 4000 rpm, also with a diff of 44.5c.
So of course I flipped the fan around and tried again. The ambient went up to 18c from 17.5c. Trivial, right? But the diff with the San Ace Silent in push mode was 50c.
Of course, I will run this comparison again tomorrow. But please, will a bunch of you test it out? Sometimes when theory meets fact, theory must die.
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2010-03-28 Did some testing today. I used OCCT set to Linpack, 1h5m, which gives a 60-minute test. I tested three fans, first pushing, then pulling. Ambient was 17.5c throughout the day. The system was shut down to reposition or replace the fan each time.
Scythe Gentle Typhoon 1850 rpm, rated at 58 cfm.
Push: Temp over ambient = 52c
Pull: Temp over ambient = 52.5c
San Ace 9S1212H401, rated at 86.5 cfm.
Push: Temp over ambient = 49.5c
Pull: Temp over ambient = 50.5c
San Ace 9G1212H101, rated at 99 cfm.
Push: Temp over ambient = 48c
Pull: Temp over ambient = 48.5c
In essence, given the fact that the cpu/mb reports temps in whole numbers, there is little difference between push and pull - at most 1c favoring push.
Again, people should compare for themselves and post the results.
It was a few minutes before I noticed that the fan was sucking air rather than pushing air through the stack. So I let OCCT finish the run. An hour later, I learned that the fan, pulling air, had achieved a difference of 48.5c over ambient.
The rig is my sig rig, running at Vcore 1.28v, 4004MHz with a Vtt=1.19v, PCH=1.2V, PLL=1.9V and DRAM=1.616v. The 48.4c diff is not bad. The best I've gotten so far is with twin Ultra Kaze 3000's, at 44.5c difference, and with twin San Ace PWM fans running nearly 4000 rpm, also with a diff of 44.5c.
So of course I flipped the fan around and tried again. The ambient went up to 18c from 17.5c. Trivial, right? But the diff with the San Ace Silent in push mode was 50c.
Of course, I will run this comparison again tomorrow. But please, will a bunch of you test it out? Sometimes when theory meets fact, theory must die.
------------------------------------------------
2010-03-28 Did some testing today. I used OCCT set to Linpack, 1h5m, which gives a 60-minute test. I tested three fans, first pushing, then pulling. Ambient was 17.5c throughout the day. The system was shut down to reposition or replace the fan each time.
Scythe Gentle Typhoon 1850 rpm, rated at 58 cfm.
Push: Temp over ambient = 52c
Pull: Temp over ambient = 52.5c
San Ace 9S1212H401, rated at 86.5 cfm.
Push: Temp over ambient = 49.5c
Pull: Temp over ambient = 50.5c
San Ace 9G1212H101, rated at 99 cfm.
Push: Temp over ambient = 48c
Pull: Temp over ambient = 48.5c
In essence, given the fact that the cpu/mb reports temps in whole numbers, there is little difference between push and pull - at most 1c favoring push.
Again, people should compare for themselves and post the results.