FAQ
TL;DR: 3.5-inch HDDs need 12V for the motor and 5V for electronics; "12V is used to power the engine." Choose a 3.5" USB 3.0 enclosure with its own power. [Elektroda, Anonymous, post #16884524]
Why it matters: This FAQ helps anyone repurposing a 3.5-inch Barracuda 7200.12 avoid underpowered USB adapters, data loss, and failed power bricks.
- 3.5-inch HDDs won’t spin from USB-only power; they require a 12V supply. [Elektroda, Anonymous, post #16884524]
- 5V powers the drive’s electronics; the 3.3V SATA pin is typically unused. [Elektroda, Anonymous, post #16884609]
- Expect to pay about 100 PLN for a decent USB 3.0 3.5" enclosure. [Elektroda, ORMO_PL, post #16885096]
- Cheap multi-adapter kits can burn their bundled power supplies. [Elektroda, djtommy, post #16885146]
- Many 3.5" enclosures include an external mains power adapter. [Elektroda, Plumpi, post #16885094]
Quick Facts
- 3.5-inch HDDs won’t spin from USB-only power; they require a 12V supply. [Elektroda, Anonymous, post #16884524]
- 5V powers the drive’s electronics; the 3.3V SATA pin is typically unused. [Elektroda, Anonymous, post #16884609]
- Expect to pay about 100 PLN for a decent USB 3.0 3.5" enclosure. [Elektroda, ORMO_PL, post #16885096]
- Cheap multi-adapter kits can burn their bundled power supplies. [Elektroda, djtommy, post #16885146]
- Many 3.5" enclosures include an external mains power adapter. [Elektroda, Plumpi, post #16885094]
Can I use a 2.5-inch USB–SATA adapter to run a 3.5-inch Barracuda 7200.12?
No. 2.5-inch-only USB–SATA adapters lack 12V output. Your 3.5-inch drive will not spin up without 12V. Use an adapter or enclosure that supplies 12V. [Elektroda, marqqv, post #16884406]
Why won’t my 3.5-inch drive start without 12V?
The spindle motor needs 12V to start and run. Without 12V, the drive won’t move at all. As one expert put it, “12V is used to power the engine.” [Elektroda, Anonymous, post #16884524]
What does the 5V line on a 3.5-inch HDD do?
5V powers the drive’s onboard electronics, including controller ICs. Some designs also use it for actuator control. The forum notes 5V is for the electronics. [Elektroda, Anonymous, post #16884609]
Is the 3.3V pin on the SATA power connector used here?
Not generally. The thread states the 3.3V pin is present but unused on these drives and setups. [Elektroda, Anonymous, post #16884609]
Will USB 2.0 power a 3.5-inch HDD if I use two ports?
It’s unreliable. Some users report needing two USB 2.0 ports just to power certain setups, and disconnections can occur after spin-up. Use a mains-powered enclosure. [Elektroda, Anonymous, post #16884524]
What’s safer: a bare USB–SATA adapter or a full 3.5-inch enclosure?
A quality 3.5-inch USB 3.0 enclosure with its own power is the safer, cleaner choice. One recommended option was described as “great.” [Elektroda, Anonymous, post #16885107]
How much should I budget for a reliable 3.5-inch USB 3.0 enclosure?
Plan around 100 PLN for a decent, reliable enclosure that supports USB 3.0 performance and includes proper power. [Elektroda, ORMO_PL, post #16885096]
Do some 2.5-inch enclosures step 5V up to 12V for 3.5-inch drives?
Some have internal 5V→12V converters, but many lack the current capacity for 3.5-inch motors. Results vary and instability is common. [Elektroda, Anonymous, post #16884524]
Are cheap all-in-one USB–SATA/IDE kits safe for 3.5-inch drives?
Be cautious. A user reported the bundled PSU burned on first use, though the disk survived. Reliability varies widely with these kits. [Elektroda, djtommy, post #16885146]
Can I run a 3.5-inch drive without any enclosure?
You can, but you’ll add clutter and need another wall outlet. It also offers no physical protection. A proper enclosure is cleaner. [Elektroda, Anonymous, post #16885085]
How do I set up my 3.5-inch HDD as an external drive?
- Buy a 3.5-inch USB 3.0 enclosure that includes an external power adapter.
- Insert the drive, secure it, and connect SATA power/data inside.
- Plug the enclosure into mains and USB, then format if needed. [Elektroda, Plumpi, post #16885094]
Should I choose USB 3.0 or USB 2.0 for this drive?
Choose USB 3.0. It improves throughput and is recommended for easier portability and performance with 3.5-inch drives. [Elektroda, ORMO_PL, post #16885096]
What did the original poster decide after testing options?
They chose to buy a 3.5-inch enclosure like the one recommended, resolving the issue and avoiding underpowered adapters. [Elektroda, baszawez, post #16885229]
