NAS vs Repurposed PC Cost Comparison: Is an Old PC Really Cheaper?

Worked Example: A NAS at the Maker's Figures, a PC at NTK's Planning Figures

Synology DS425+ against "Old desktop, Intel 7th to 8th gen" (NTK planning figures 35 W idle, 95 W load), the PC at load 25% of the day. The two sides are not measured the same way: the NAS figures are the maker's own states with its drives fitted, the PC figures are NTK planning assumptions without drives.

• PC: (95 W x 6 h + 35 W x the other hours) x 365 days = 438.0 kWh a year, before its drives.
• NAS with no drive sleep: 28.25 W Access x 24 h x 365 days = 247.5 kWh a year, counted at the maker's busy figure all day; a NAS that is idle most of the day will usually use less.
• NAS with the drives asleep 8 hours a day at 6.1 W HDD Hibernation: 182.8 kWh a year.

What each side costs to run, and whether the NAS pays for itself, depends on your electricity rate and the NAS price (NTK market price for the DS425+: $899, 2026-10-23), so the calculator works it out: open this example in the calculator, or with 8 hours of drive sleep, then pick your state or enter your rate.

Is My Old PC Good Enough for a NAS?

Two things decide it: whether it can do the job, and what it costs to keep running. For the running cost, start from its idle watts. The table below is NTK's planning figure for each generation of PC, for the CPU and chassis without drives. Your PC can be well above or below it, so measure it at the wall with a plug-in power meter and enter that figure in the calculator.

NTK planning assumptions, not measurements: measure your own PC at the wall with a plug-in power meter. CPU and chassis only: drives are not included (add the drives' own watts, or measure the whole PC with its drives). * No load figure exists for these desktops, so NTK carries its desktop load figure of 95 W as an editable planning assumption. For what a PC costs to run at your rate, enter it in the calculator above.

Questions to ask before you repurpose it

• How many drives does it hold, and how many SATA ports does it have? If it needs a SATA or HBA card or an external enclosure, add the cost under Extra hardware.
• What does it draw at the wall when idle? A plug-in power meter tells you; the calculator does the rest.
• Where will it live? A desktop case is bigger and often louder than a NAS, and swapping a drive usually means opening it.
• Which NAS software will you run, and does it cost anything? TrueNAS Community Edition is free, openmediavault is open source (GPLv3) and Unraid is a paid licence.

How We Calculate

NAS energy. The maker's two states: (busy watts x the hours the drives are awake + drives asleep watts x the hours they sleep) x 365 days, divided by 1,000. With 0 hours of sleep the NAS is counted at its busy figure all day. Makers measure that figure during file transfers or typical operation, and Synology says its figures are not meant to be minimum or maximum power consumption figures (Synology, checked 2026-10-14), so a NAS that is idle most of the day will usually use less. A figure you measured at the wall is better: choose Custom NAS and enter it as the busy watts.

PC energy. (load watts x the hours at load + idle watts x the other hours) x 365 days, divided by 1,000, with your drives' watts added to both.

Cost = annual kWh x your rate. Total = hardware + extra hardware + software + electricity over the period. Break-even = the NAS's extra upfront cost divided by the yearly running cost it saves, with four cases: the NAS pays back after N years, it is ahead from day one, the PC catches up after N years, or it never pays back. A year is 8,760 hours.

NAS power figures and prices

Market prices are NTK's median across at least three Australian retailers with fresh listings, 2026-10-23. A model without one needs your price.

NAS software for a PC

• From TrueNAS 25.04, TrueNAS SCALE is called TrueNAS Community Edition; TrueNAS CORE is in its maintenance phase. TrueNAS Community Edition is free and open source. (TrueNAS (iXsystems), checked 2026-10-07)
• Unraid Starter: listed at $49 one time, 6 storage devices, 1 year of updates. (unraid.net, checked 2026-10-07)
• Unraid Unleashed: listed at $109 one time, unlimited storage devices, 1 year of updates. (unraid.net, checked 2026-10-07)
• Unraid Lifetime: listed at $249 one time, unlimited storage devices, lifetime updates. (unraid.net, checked 2026-10-07)
• Unraid's pricing page shows its prices with no currency code; NTK shows them as listed and does not convert them. Enter what you pay in the calculator.
• openmediavault is a Debian Linux based NAS system released under the GPLv3 licence. (openmediavault, checked 2026-10-07)

Electricity rates used

Enter the rate from your bill for your own figure; on a time of use plan, use your average (blended) rate.

Assumptions NTK made

Method last reviewed: 2026-10-14. NAS power and software facts last checked at source: 2026-10-07. Market prices: 2026-10-23. Electricity rates dated from: 2026-09-25.

NBN upload speeds affect your NAS remote access capability regardless of hardware. See our NBN Remote Access Reality Checker for AU-specific limits. Your first step for a faulty product is usually the retailer that sold it. The ACCC explains your rights under the Australian Consumer Law at accc.gov.au.

Frequently Asked Questions