Sound Mitigation#
This documentation is part of NVIDIA DGX SuperPOD: Data Center Design Featuring NVIDIA DGX H100 Systems.
The Acoustic Power (LWA,m) of each DGX H100 system is rated at 98.7 dB at 80% Fan PWM (30 °C/86 °F). Noise levels up to106 dB per server are possible. When multiple servers are placed within proximity, such as a row of server racks, each containing multiple servers, the noise level increases logarithmically. Table 20 shows the aggregate sound level of a given quantity of servers based on 98.7 dB acoustic power of a single server. These numbers do not account for differences in distance that may result from different floor layouts of the racks.
Server Quantity |
Difference in Sound Intensity (dB) relative to single server |
Total System Sound Level at This Server Qty (dB) |
|---|---|---|
1 |
0.00 |
98.70 |
2 |
3.01 |
101.71 |
3 |
4.77 |
103.47 |
4 |
6.02 |
104.72 |
5 |
6.99 |
105.69 |
6 |
7.78 |
106.48 |
7 |
8.45 |
107.15 |
8 |
9.03 |
107.73 |
9 |
9.54 |
108.24 |
10 |
10.00 |
108.70 |
11 |
10.41 |
109.11 |
12 |
10.79 |
109.49 |
13 |
11.14 |
109.84 |
14 |
11.46 |
110.16 |
15 |
11.76 |
110.46 |
16 |
12.04 |
110.74 |
17 |
12.30 |
111.00 |
18 |
12.55 |
111.25 |
19 |
12.79 |
111.49 |
20 |
13.01 |
111.71 |
21 |
13.22 |
111.92 |
22 |
13.42 |
112.12 |
23 |
13.62 |
112.32 |
24 |
13.80 |
112.50 |
25 |
13.98 |
112.68 |
26 |
14.15 |
112.85 |
27 |
14.31 |
113.01 |
28 |
14.47 |
113.17 |
29 |
14.62 |
113.32 |
30 |
14.77 |
113.47 |
31 |
14.91 |
113.61 |
32 |
15.05 |
113.75 |
Further, while the preceding numbers represent the noise being transmitted from the servers themselves, the acoustic properties (lack of absorbent surfaces, reflection of emitted sound, etc.) and ambient noise level of the room environment can add significantly to these measurements.
Table 21 provides a reference for these noise levels, relative to commonly experienced sounds.
Source |
Intensity |
dBA |
|---|---|---|
Threshold of Hearing (TOH) |
1*10-12 W/m2 |
0 dB |
Rustling Leaves |
1*10-11 W/m2 |
10 dB |
Whisper |
1*10-10 W/m2 |
20 dB |
Normal Conversation |
1*10-6 W/m2 |
60 dB |
Busy Street Traffic |
1*10-5 W/m2 |
70 dB |
Vacuum Cleaner |
1*10-4 W/m2 |
80 dB |
Large Orchestra |
1*10-3 W/m2 |
98 dB |
Headphones at Maximum Level |
1*10-2 W/m2 |
100 dB |
Front Rows of Rock Concert |
1*10-1 W/m2 |
110 dB |
Threshold of Pain |
1*101 W/m2 |
130 dB |
Military Jet Takeoff |
1*102 W/m2 |
140 dB |
Instant Perforation of Eardrum |
1*104 W/m2 |
160 dB |
For reference, a difference of 10 dB(a) represents a 100% increase in perceived sound level. As show in the previous tables, a row of 32 DGX H100 systems can be louder than a major rock concert, and over four times louder than a typical vacuum cleaner, even with the fans running at only 80% PWM.
The maximum acceptable unprotected exposure limit for a standard 8-hour duty cycle is a time weighted average of 85 dBA. The purpose of PPE and engineering controls is to attenuate audible sound down to 85 dBA or lower. If that is not possible, the worker’s duty cycles must be reduced to the durations allowed by the remaining unattenuated dBA. So, for example, if with maximum hearing protection the audible sound level is still 100 dBA, then the duty cycle must be reduced to 15 minutes.
The highest NRR rating for PPE earplugs is 33, and the highest available NRR rating for earmuffs is 31. These values reflect the level of noise protection available for each device when worn alone. Combining earplugs with earmuffs can offer an NRR protection level of 36.
The NRR Rating of a PPE Hearing protection device does not represent actual sound attenuation levels achieved in practical use. The formula for determining actual attenuation is NRR -7 * 0.5. When two PPE devices are used, this calculation is performed on the higher rated device, and 5 dBA is added to the result regardless of the NRR value of the second device.
Practical attenuation beyond 18 dBA requires mechanical sound mitigation or elimination (a.k.a. engineering controls) and is not attainable with PPE alone.
Data center staff should undergo routine hearing tests by a certified audiologist to establish a baseline and identify any hearing loss over time, so that appropriate and timely interventions can be made.
Table 22 illustrates the maximum exposure limits for certain sound levels, as regulated by the National Institute for Occupational Safety and Health (NIOSH).
Sound Level (dBA) |
Hours |
Minutes |
Seconds |
|---|---|---|---|
82 |
16 |
0 |
0 |
85 |
8 |
0 |
0 |
88 |
4 |
0 |
0 |
91 |
2 |
0 |
0 |
94 |
1 |
0 |
0 |
97 |
0 |
30 |
0 |
100 |
0 |
15 |
0 |
103 |
0 |
7 |
30 |
106 |
0 |
3 |
45 |
109 |
0 |
1 |
53 |
112 |
0 |
0 |
56 |
115 |
0 |
0 |
28 |
118 |
0 |
0 |
14 |
121 |
0 |
0 |
7 |
124 |
0 |
0 |
3 |
127 |
0 |
0 |
1 |
130 |
0 |
0 |
0.5 |