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StashRaid

Storage Parameters

Usable Capacity

12 TB

Fault Tolerance

4

Array Resilience

Architecture

RAID 5 • Parity

Fault Tolerance

1 Concurrent Failures Allowed

Current Configuration

RAID 5 (Parity)

12 TB Usable

Total RAW: 16 TB

Disk 01DATA
Disk 02DATA
Disk 03DATA
Disk 04PARITY

Total Drives

4 x 4 TB

Efficiency

75% Utilized

Usable: 12 TBWasted to redundancy: 4 TB

Pros & Cons

  • PRO: Good balance of capacity/speed/safety

  • PRO: Cost-effective redundancy

  • CON: Slower writes due to parity calculation

    This setup prioritizes redundancy but has associated performance or capacity costs.

NAS Power Consumption & Total Cost of Ownership

Electricity is the hidden cost of running a NAS. A fully loaded 12-bay box can draw 150–250 W 24/7, adding hundreds to your annual electric bill. This guide breaks down where that power goes — drive type, system components, PSU efficiency — and how to calculate your true TCO over 3 and 5 years.

Drive Power Consumption by Type

Hard drives account for 40–60% of a NAS’s total draw. The single biggest variable is drive type. Below are real-world averages for the three common categories:

Drive TypeIdle (W)Active (W)Annual kWhCost/yr @ $0.12
3.5" 5400 RPM HDD46.535$4.20
3.5" 7200 RPM HDD5.5948$5.78
SATA / NVMe SSD0.33.53$0.32

5400 vs 7200 RPM — the $15–30/year per-drive difference

A 7200 RPM drive draws 2.5–3 W more at idle than a 5400 RPM equivalent. That’s ~$18–28/year per drive at $0.12/kWh. In an 8-bay NAS you save ~$140–220/year by choosing 5400 RPM. Over 5 years that’s $700–1,100 saved — enough for a second set of drives. For bulk media storage, 5400 RPM is the cost-optimal choice.

System Power Breakdown

The motherboard, CPU, RAM, HBA, fans, and NIC together draw 35–90 W depending on your hardware choices:

ComponentTypical (W)Notes
Low-power CPU (N100 / Celeron)10Idle ~6W, load ~20W
Mid-range CPU (i3 / Ryzen 3)25Idle ~15W, load ~45W
High-end CPU (i5–i7 / Ryzen 5–7)45Idle ~25W, load ~80W
8/16/32 GB DDR4 RAM3/5/9~0.3W per GB heavy load
HBA / SAS controller10LSI 9207-8i ~8–12W
10 GbE NIC8Real world 6–10W
Case fans (3× 120mm)6Noctua NF-A12x25 ~2W each
Motherboard + chipset15ATX ~15W, ITX ~10W

PSU Efficiency Curves

Power supplies are most efficient (80–94%) at 50–80% load. A PSU at 20% load may be only 75% efficient, wasting 25% as heat. Right-size your PSU — a 150 W Gold unit at 50% load beats a 500 W Bronze at 14% load. For low-power builds, consider a PicoPSU (90–96% efficient).

Yearly Electricity Cost: 4-Bay vs 8-Bay vs 12-Bay

Total AC watts (including PSU overhead) at various US electricity rates. Assumes drives active. See below for spin-down savings.

NAS ConfigAC W (idle)AC W (active)@ $0.08@ $0.12@ $0.16@ $0.20@ $0.30
4-Bay (5400)7284$59$88$117$146$220
4-Bay (7200)7995$67$100$134$167$250
8-Bay (5400)105127$89$134$178$223$334
8-Bay (7200)118150$105$158$210$263$394
12-Bay (5400)137170$119$179$238$298$447
12-Bay (7200)157203$142$214$285$356$534

Real-world example: An 8-bay 7200 RPM NAS at $0.16/kWh (common in CA/NY) costs ~$228/year. Over 5 years that’s $1,140 — more than the drives. Switching to 5400 RPM saves ~$90/year.

Idle vs Active Power & Spin-Down Savings

Most NAS drives sit idle 70–90% of the time. In idle, a 5400 RPM HDD draws ~4 W vs ~6.5 W active. Spin-down saves real money but has trade-offs:

ScenarioDrawCost/yr (4-bay, $0.12)Pros / Cons
Always active~52 W AC~$55Fastest wake, lowest head wear
Spin-down after 30 min~25 W idle / ~52 W active~$35 (~35% savings)~$20/yr saved; more load/unload cycles
System sleep / WoL~5 W~$5 (~90% savings)Best savings, but NAS is offline

Note on wear: Frequent spin-up/down (>10/day) on enterprise 24/7 drives can reduce lifespan. For consumer drives rated at 2M-hour MTBF the impact is minimal. The main cost is latency — waiting 5–15 s for a drive to spin up on access.

Total Cost of Ownership: 3-Year and 5-Year

The cheapest NAS balances hardware, drive, and electricity costs over its useful life. Below: three 8-bay builds at $0.14/kWh, 50/50 idle/active.

BuildUpfront (HW + 8× drives)5-Yr Electricity5-Yr TCO
Budget 5400$1,070$711$1781
Mainstream 7200$1,430$822$2252
All-SSD$1,490$524$2014

Bottom line: The 5400 RPM budget build saves ~$700 over 5 years vs the 7200 RPM build — entirely from electricity. All-SSD is competitive when you factor in lower power and zero drive replacement.

Quick Formulas

Annual kWh = Watts × 24 × 365 ÷ 1000

Annual Cost = kWh × $/kWh

AC Watts = DC Watts ÷ PSU Efficiency

5-Year TCO = Purchase Price + (Annual Cost × 5)

Quick rule of thumb: Every 10 W continuous draw costs ~$10.50/year at $0.12/kWh. A 200 W system costs ~$210/year.

Related Guides & Tools

Build Planner

Match your CPU, PSU, and drives to your power budget.

Gear Recommender

Get drive and hardware picks for your needs.

Drive Failure Math

MTBF, AFR, and power cycling explained.

Power Calculator

Estimate your exact build’s power and cost.

FAQ

How much power does a typical 4-bay NAS use?

~50–70 W idle, ~75–100 W active including PSU losses. At $0.12/kWh that's $55–105/year.

Can I save money with 5400 RPM drives?

Yes — each 7200 RPM drive uses ~2.5–3 W more. In an 8-bay NAS that's $140–220/year saved. Over 5 years: $700–1,100.

Should I spin down drives when idle?

Yes — it saves $15–40/year in a multi-bay NAS. Limit to 1–2 spin-downs/day if longevity is a concern, and disable for frequently-accessed data.

How do I measure my actual NAS power draw?

Use a Kill-A-Watt plug-in meter for real AC watts. Multiply by 24×365/1000 for kWh, then by your utility rate. For a quick estimate use our NAS Power Calculator.

Figures are typical averages. Actual draw depends on drive model, workload, and ambient temperature. Always measure your specific build.