Exam CDCS topic 1 question 1 discussion

Actual exam question from Exin's CDCS

Question #: 1
Topic #: 1

A 5kW (power consumption) server keeps crashing with the message ‘temperature too high’.
- The intake temperature is measured at 25 °C/77 °F and a relative humidity (RH) level of 50%.
- The exhaust temperature is 29 °C/84 °F and 45% RH.
- The raised floor is providing adequate amount of CFM/CMH at a reasonable velocity.
- The pressure under the raised floor is approximately 25 Pa/0.1 inch H20.
Analyze the situation and indicate what the most likely cause is for this server to crash.

A. Dust inside the server causing issues with convection-based heat transfer
B. The exhaust temperature is exceeding the ASHRAE recommended values
C. The raised floor pressure is too low and/or the raised floor tile % opening is not adequate
D. No cause could be determined as the CFM/CMH of the air conditioning equipment is not stated

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Suggested Answer: A 🗳️

by xyahiax at June 24, 2025, 4:52 p.m.

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xyahiax

2 weeks, 4 days ago

Selected Answer: A

The most likely answer is: **A. Dust inside the server causing issues with convection-based heat transfer.** Here’s why: - **Intake temperature (25 °C)** and **exhaust temperature (29 °C)** are **well within ASHRAE's recommended thermal guidelines** for Class A1 servers, which allow inlet temperatures up to 27 °C or higher, depending on class. - The **raised floor airflow and pressure (25 Pa)** are stated to be adequate, and there’s no indication of poor tile opening or insufficient CFM in general. - Option **D** mentions that the CFM/CMH is not stated, but the scenario clearly says it's "adequate," which reasonably rules out D. - That leaves **A**, which points to an **internal heat transfer issue**—if dust has accumulated on heat sinks or within fans, **it could block airflow within the server**, leading to **localized overheating**, even while intake and exhaust temperatures remain normal

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