Noise levels at different speeds

Pump

This is an EK D5 pump in a FLT120 reservoir.

PWM	RPM	Noise
40%	1950	Silent
50%	2500	Just audible
60%	3060	Quiet
68%	3520	Mild
75%	3950	Max acceptable level
100%	4775	Pretty loud

Pump speed vs flow

Same EK D5 pump in a FLT120 reservoir.

Pump PWM	Pump RPM	Flow meter volume	Flow meter tacho	Notes
50%	2495 rpm	0.6 L/min	13.75 rps	-
47%	2330 rpm	0.45 L/min	11 rps	-
35%	1650 rpm	0.1 L/min	3 rps	Sometimes triggers low-flow alarm
34%	1620 rpm	no reading	no reading	Always triggers low-flow alarm

Fan

Arctic P12 PWM PST

I think this was with two fans.

PWM	RPM	Noise
20%	530	Silent
35%	870	Effectively silent
40%	965	Just audible
50%	1150	Pleasant
75%	1575	Max acceptable level
100%	1925	Pretty loud

Heat loads

Components	Estimated load (Watts approx)
Idle	25
Full CPU	120
Full GPU	250

Results

This is mostly about finding a sweet spot for being quiet at idle, and sufficiently cool under load, without being too noisy.

This is the new loop layout, after Maru helped out with reworking everything. 280mm radiator with 2x 140mm Corsair maglev fans.

Low speeds

34% fan - 655 rpm
45% pump - 2200 rpm
0.5L/min flow rate - 12rps on the meter

Load	CPU temp	GPU temp	Loop temp	Notes
CPU only	84 C	29 C	28 C	Cinebench R23
GPU only	63 C	54 C	33 C	Furmark
GPU and half-CPU	90 C	59 C	37 C	Furmark and Cinebench limited to half usual threads
GPU and full-CPU	n/a	n/a	n/a	Not tested because the CPU throttles at 90C

Loop speeds are simply too low to get heat out of the chip fast enough, the CPU will lower the boost ceiling to try and stay at 90 degrees.

With some GPU undervolting we get a very healthy improvement in temps:

Load	CPU temp	GPU temp	Loop temp	Notes
GPU only - stock	63 C	54 C	33 C	-
GPU only - undervolted	57 C	48 C	31 C	-

Medium speeds

50% fan - 1000 rpm
60% pump - 3060 rpm
1.0L/min flow rate - 24rps on the meter

Load	CPU temp	GPU temp	Loop temp	Notes
CPU only	82 C	27 C	27 C	Cinebench R23
GPU only	54 C	48 C	31 C	Furmark
GPU and half-CPU	82 C	51 C	33 C	Furmark and Cinebench limited to half usual threads
GPU and full-CPU	90 C	52 C	35 C	Furmark and Cinebench with unlimited threads

This is a fair bump in flow, which suggests that the CPU isn't being cooled effectively when running at fill-tilt, I think. I wish I'd taken note of the CPU speeds, because then the CPU-only and CPU+GPU test cases could be compared.

High speeds

60% fan - 1200 rpm
100% pump - 4800 rpm
2.0L/min flow rate - 47rps on the meter

Load	CPU temp	GPU temp	Loop temp	Notes
CPU only	83 C	-	29 C	Cinebench R23 - 140W
GPU only	55 C	48 C	33 C	Furmark - 280W total power (230W GPU + 50W CPU)
GPU and half-CPU	82 C	50 C	34 C	Furmark and Cinebench limited to half usual threads - 340W power (230W + 110W)
GPU and full-CPU	90 C	-	34 C	Furmark and Cinebench with unlimited threads

Not sure why I don't have GPU temps for all test cases. Very similar to medium flow case, suggesting no benefit from the higher speeds. CPU still hitting it's 90 degree ceiling.

GPU undervolting

Poking at this while running Furmark.

34% fan
45% pump

Stock voltage settings

54 degrees C (loop or GPU core?)
230W GPU power draw
83fps
1068 mV
1950 MHz (GPU core?)

Undervolt applied

47 degrees C (loop or GPU core?)
185W GPU power draw
83fps
950 mV
1950 MHz (GPU core?)