Success!!!
OK, I don't have an SPL meter to prove I got it below 50dba idle, but its SO QUIET now!
Went ahead with a straight fan replacement. Used Evercool EC8038HH12BP fans, purchased from FrozenCPU.com for $14.99/each. I also picked up some in-line male 4-pin PWM fan connectors. I removed the original fans, cut the dell cable right after the point that they join the power/neutral wires from the two PSUs, put the male 4-pin connectors on the cable and connected it to the Evercool fans. Then I re-installed the new fans.
Before I started I configured 3 nodes with 2x L5638 Xeons & 48Gb ECC RAM (don't have the CPUs for the 4th sled right now). I loaded an SSD for each with Win-7 and Prime95 for a CPU load stress test.
Before: With three Nodes running Win-7, idle, it was unacceptably loud. Loud enough to be heard through the walls in the house (C6100 is in the garage). Running Prime-95 on three nodes it just SCREAMED. Fans were running about 20,000 RPM (which is well short of their max) and the CPUs settle in from 67c to 75c - hot, but not out of range for this CPU. But this sucker is LOUD.
After: With three Nodes running Win-7, idle, it was barely audible all(!). Not silent. You could definitely hear it if you stood right next to it. The garage has a good deal of ambient noise from other equipment (mostly a Juniper EX2500) and in that environment the modified C6100 did not add any materiel noise. Fans ramped down to about 1,200 RPM - which actually raised a fan alarm on the BMC. Running Prime-95 on all three nodes was interesting. After just a few minutes the fans ramped up to 3,500 RPM, which is just about 50% of rated speed. At that speed the C6100 became quite noticeable in the garage, but not offensively loud. You could still not hear it inside the house, which is the real test. But the CPU temps were on a very slow creep up into the high-70s. Any time one of the CPUs hit the high-temp alarm point - which the BMC set as 81C for this CPU - the fans went to full speed (reported as ~7,000 RPM, even though it is spec'd at 6,500 RPM). When they hit this speed they were too loud - very noticeable inside the house. But they only ran at this speed for 30 seconds or so and dropped the CPU temps quickly back into the low-60s/high-50s - then the fans slowed again, and the slow temperature creep started again. It is running stable now in this cycle of 10-15 minute "acceptable but loud" followed by 30 seconds of "screaming loud" and has been running that way for about 2 hours.
I seriously doubt I will run workloads anywhere close to this intense very often...so I don't expect to hear the fans ramp like this.
I consider this mod a complete success!
A few pictures:
The fans and 4-pin connectors:
The original Delta fan:
The connector mod on the Dell fan cable, with Evercool fan plugged in:
The fully modded Evercool fan:
OK, I don't have an SPL meter to prove I got it below 50dba idle, but its SO QUIET now!
Went ahead with a straight fan replacement. Used Evercool EC8038HH12BP fans, purchased from FrozenCPU.com for $14.99/each. I also picked up some in-line male 4-pin PWM fan connectors. I removed the original fans, cut the dell cable right after the point that they join the power/neutral wires from the two PSUs, put the male 4-pin connectors on the cable and connected it to the Evercool fans. Then I re-installed the new fans.
Before I started I configured 3 nodes with 2x L5638 Xeons & 48Gb ECC RAM (don't have the CPUs for the 4th sled right now). I loaded an SSD for each with Win-7 and Prime95 for a CPU load stress test.
Before: With three Nodes running Win-7, idle, it was unacceptably loud. Loud enough to be heard through the walls in the house (C6100 is in the garage). Running Prime-95 on three nodes it just SCREAMED. Fans were running about 20,000 RPM (which is well short of their max) and the CPUs settle in from 67c to 75c - hot, but not out of range for this CPU. But this sucker is LOUD.
After: With three Nodes running Win-7, idle, it was barely audible all(!). Not silent. You could definitely hear it if you stood right next to it. The garage has a good deal of ambient noise from other equipment (mostly a Juniper EX2500) and in that environment the modified C6100 did not add any materiel noise. Fans ramped down to about 1,200 RPM - which actually raised a fan alarm on the BMC. Running Prime-95 on all three nodes was interesting. After just a few minutes the fans ramped up to 3,500 RPM, which is just about 50% of rated speed. At that speed the C6100 became quite noticeable in the garage, but not offensively loud. You could still not hear it inside the house, which is the real test. But the CPU temps were on a very slow creep up into the high-70s. Any time one of the CPUs hit the high-temp alarm point - which the BMC set as 81C for this CPU - the fans went to full speed (reported as ~7,000 RPM, even though it is spec'd at 6,500 RPM). When they hit this speed they were too loud - very noticeable inside the house. But they only ran at this speed for 30 seconds or so and dropped the CPU temps quickly back into the low-60s/high-50s - then the fans slowed again, and the slow temperature creep started again. It is running stable now in this cycle of 10-15 minute "acceptable but loud" followed by 30 seconds of "screaming loud" and has been running that way for about 2 hours.
I seriously doubt I will run workloads anywhere close to this intense very often...so I don't expect to hear the fans ramp like this.
I consider this mod a complete success!
A few pictures:
The fans and 4-pin connectors:
The original Delta fan:
The connector mod on the Dell fan cable, with Evercool fan plugged in:
The fully modded Evercool fan:
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