Measure temperatures under load and label the lab's cables

short · 40 min · Objective 1.1

Task

Measure how the temperatures inside a real machine respond to load and to blocked airflow, and then label every cable in your lab to a scheme that lets someone else trace any connection without following it by hand. Both are routine in a server room, and both are skipped until the day they are needed.

Steps

  1. Let the PC idle for five minutes, then save the output of sensors to lab/cooling/idle.txt.
  2. Run stress-ng --cpu 0 --timeout 300s and, near the end, save sensors to lab/cooling/load.txt. Note the fan speeds if the output shows them.
  3. Record the processor package or core temperature from each file in lab/cooling/summary.csv with header state,cpu_c,fan_rpm and one row each with state idle and load, temperatures as plain numbers.
  4. Invent a cable labelling scheme that encodes both ends, such as PC1-NIC1 > SW1-P03. Label every network and power cable in your lab at both ends.
  5. Record every cable in lab/cabling/cables.csv with header id,end_a,end_b,type,length_m, using the same identifiers as the physical labels.

Verify

These checks run in a POSIX shell: Terminal on macOS or Linux, and on Windows Git Bash (it comes with Git for Windows) or WSL. A stock Windows PowerShell or Command Prompt has no awk or grep, so there the first line fails.

grep -Ec 'Package|Core|Tctl|temp' lab/cooling/idle.txt lab/cooling/load.txt
awk -F, 'NR>1 {t[$1]=$2} END {print "idle "t["idle"]" C, load "t["load"]" C"; exit !(t["load"]>t["idle"])}' lab/cooling/summary.csv
awk -F, 'NR>1 && ($2=="" || $3=="") {bad++} END {print bad+0" cable(s) missing an end"}' lab/cabling/cables.csv
awk -F, 'NR>1 {c[$1]++} END {for (i in c) if (c[i]>1) d++; print d+0" duplicate id(s)"}' lab/cabling/cables.csv

The load temperature must be higher than idle, or the stress test did not run; the second command exits non-zero in that case. Expect zero cables missing an end and zero duplicate identifiers. A cable recorded with only one end is the cable someone unplugs to find out where it goes.

Notes

Server processors throttle long before damage, so a load temperature in the 80s or 90s Celsius on a desktop is not by itself a fault. What the exercise shows is how quickly temperature follows load, which is why a failed fan or a missing blanking panel shows up in minutes, not days.

This is an independent study companion for CompTIA Server+ SK0-005 and is not produced by or endorsed by CompTIA.