Buying Guide
The Best PSUs for Home Office PCs
Four power supplies compared, from the Thermaltake Smart BM3 650W to the Seasonic Focus GX-750, with the trade-offs of each named.
By The PC Journal editorial team
11 min read4 products evaluated
An office PC spends most of its time at low load, so a zero-RPM fan mode keeps it quiet. Every pick is 750W or less and lists a zero-RPM fan mode, ordered from the lowest price.
Our comparison rests on published figures for wattage, native 12V-2x6 cables and warranty; where a maker leaves out native 12V-2x6 cables, we say so, and no figure here comes from our own testing.
Quick Picks
Our 4 recommendations at a glance. Tap a pick for the full verdict.
Lowest Price Here
Thermaltake Smart BM3 650W
A lower price than the SAMA GT650 White and the rest when we checked.
Best for: Spending as little as possible.
Our take Check price for Thermaltake Smart BM3 650W (opens in a new tab)
Also Consider
SAMA GT650 White
An ECO silent mode for low-load quiet.
Best for: Buyers who want ECO silent mode for low-load quiet.
Our take Check price for SAMA GT650 White (opens in a new tab)
Strong Alternative
MONTECH Century II 650W
A 10-year warranty at a low price.
Best for: Buyers who want 10-year warranty at a low price.
Our take Check price for MONTECH Century II 650W (opens in a new tab)
Highest Rated Output
Seasonic Focus GX-750 (ATX 3.1)
The highest rated output here (750W).
Best for: Buyers who put rated output first.
Our take Check price for Seasonic Focus GX-750 (ATX 3.1) (opens in a new tab)
| Pick | Why it’s here | Best for | Price |
|---|---|---|---|
| A lower price than the SAMA GT650 White and the rest when we checked. | Spending as little as possible. | Check price for Thermaltake Smart BM3 650W (opens in a new tab) |
| An ECO silent mode for low-load quiet. | Buyers who want ECO silent mode for low-load quiet. | Check price for SAMA GT650 White (opens in a new tab) |
| A 10-year warranty at a low price. | Buyers who want 10-year warranty at a low price. | Check price for MONTECH Century II 650W (opens in a new tab) |
| The highest rated output here (750W). | Buyers who put rated output first. | Check price for Seasonic Focus GX-750 (ATX 3.1) (opens in a new tab) |
Our Picks
Lowest Price Here1 of 4
Thermaltake Smart BM3 650W on Amazon (opens in a new tab)
The Thermaltake Smart BM3 650W stands out for Japanese 105°C main capacitor, and it adds semi-modular cables: fixed main cables, detachable extras.
Best for
- Spending as little as possible.
Skip if
- Skip it if this is a deal-breaker for you: a shorter 5-year warranty.
Why we like it
It also offers a 650W rated output and offers a 5 years warranty. It is 80 Plus Bronze and ATX 3.1 compliant for PCIe Gen 5 cards, with industrial-grade protections built in. On rated output it ties with the SAMA GT650 White and the MONTECH Century II 650W at 650W.
A bronze 80 plus rating is unique to it among these picks, while the Seasonic Focus GX-750 uses a gold 80 plus rating. It shares a black colour with the MONTECH Century II 650W and Seasonic Focus GX-750; the SAMA GT650 White goes with a white colour. The Thermaltake Smart BM3 650W has no stated native 12V-2x6 cable; confirm the cable kit before pairing it with a 16-pin card.
It was the cheapest of the group when we checked; the SAMA GT650 White was the next step up. Buyers who need a confirmed native 12V-2x6 cable count should compare it with the SAMA GT650 White, which offers 1.
Key dimensions & specs
- Wattage: 650W
- Warranty: 5 years
- 80 Plus rating: Bronze
- ATX version: ATX 3.1
- Form factor: ATX
- Cabling: Semi-modular
- Fan: 120mm
- Fan stop: Yes
- Colour: Black
Pros
- A 650W rating
- ATX 3.1 compliance
- A fan that stops at low load
- Japanese 105°C main capacitor
Cons
- A shorter 5-year warranty
- Only 80 Plus Bronze efficiency
- No published native 12V-2x6 cable count
Also Consider2 of 4
SAMA GT650 White on Amazon (opens in a new tab)
SAMA's GT650 White is a fully modular white unit with embossed white cables, a native 12V-2x6 cable and an ECO silent mode.
Best for
- Buyers who want ECO silent mode for low-load quiet.
Skip if
- Pass if a published warranty matters; this one has none.
Why we like it
Japanese capacitors support long-term durability, and a native 12V-2x6 connector feeds current graphics cards. It is 80 Plus Gold rated. It matches the Thermaltake Smart BM3 650W and the MONTECH Century II 650W on rated output (650W).
It shares fully modular cabling with the MONTECH Century II 650W; the Thermaltake Smart BM3 650W goes with semi-modular cabling. No other pick in this guide offers a white colour; compare the Thermaltake Smart BM3 650W, which has a black colour. The SAMA GT650 White comes with a native 12V-2x6 cable, so a 16-pin card plugs in without an adapter.
No depth is rated for the SAMA GT650 White, so check the maker's page against your case's PSU bay. It was priced above the Thermaltake Smart BM3 650W and below the MONTECH Century II 650W at the time of writing. There is no published warranty figure, whereas the MONTECH Century II 650W offers 10 years.
Key dimensions & specs
- Wattage: 650W
- Native 12V-2x6 cables: 1
- ATX version: ATX 3.1
- Form factor: ATX
- Cabling: Fully modular
- Fan: 120mm
- Fan stop: Yes
- Colour: White
Pros
- A 650W rating
- A native 12V-2x6 cable for 16-pin cards
- ATX 3.1 compliance
- Fully modular cables
Cons
- No published warranty
- Costs more than the Thermaltake Smart BM3 650W at the time of writing
Strong Alternative3 of 4
MONTECH Century II 650W on Amazon (opens in a new tab)
Montech's Century II 650W brings a native 12V-2x6 cable, fully modular cables and a 10-year warranty to a low-cost 80 Plus Gold unit.
Best for
- Buyers who want 10-year warranty at a low price.
Skip if
- Skip it if rated output matters most to you; the Seasonic Focus GX-750 offers 750W.
Why we like it
Its 135mm FDB fan has a zero RPM mode, and it uses 100% Japanese capacitors. It matches the Thermaltake Smart BM3 650W and the SAMA GT650 White on rated output (650W). Like the Seasonic Focus GX-750, it has a gold 80 plus rating, while the Thermaltake Smart BM3 650W uses a bronze 80 plus rating.
It shares fully modular cabling with the SAMA GT650 White; the Thermaltake Smart BM3 650W goes with semi-modular cabling. The MONTECH Century II 650W comes with a native 12V-2x6 cable, so a 16-pin card plugs in without an adapter. No depth is rated for the MONTECH Century II 650W, so check the maker's page against your case's PSU bay.
When we checked, only the SAMA GT650 White and cheaper picks cost less, and the Seasonic Focus GX-750 cost more. Rated output is its weakest area, and the Seasonic Focus GX-750 covers it better at 750W.
Key dimensions & specs
- Wattage: 650W
- Native 12V-2x6 cables: 1
- Warranty: 10 years
- 80 Plus rating: Gold
- ATX version: ATX 3.1
- Form factor: ATX
- Cabling: Fully modular
- Fan: 135mm
- Fan stop: Yes
- Colour: Black
Pros
- A 650W rating
- A native 12V-2x6 cable for 16-pin cards
- A 10-year warranty
- ATX 3.1 compliance
Cons
- Rated output trails the Seasonic Focus GX-750 (750W)
- Costs more than the Thermaltake Smart BM3 650W at the time of writing
Highest Rated Output4 of 4
Seasonic Focus GX-750 (ATX 3.1) on Amazon (opens in a new tab)
The Seasonic Focus GX-750 is built around hybrid fan control with a 135mm FDB fan, with Seasonic's OptiSink design on top.
Best for
- Buyers who put rated output first.
Skip if
- Skip it if you need to know its warranty before buying; the maker doesn't publish one.
Why we like it
On the spec sheet, it offers a 750W rated output and offers a 1 native 12V-2x6 cable count. It is 80 Plus Gold and Cybenetics Platinum certified with a native 12V-2x6 connector. Its 750W rated output is the highest here; the Thermaltake Smart BM3 650W comes next at 650W.
Like the MONTECH Century II 650W, it has a gold 80 plus rating, while the Thermaltake Smart BM3 650W uses a bronze 80 plus rating. The Seasonic Focus GX-750 comes with a native 12V-2x6 cable, so a 16-pin card plugs in without an adapter. No depth is rated for the Seasonic Focus GX-750, so check the maker's page against your case's PSU bay.
At our last price check it topped the group, with the MONTECH Century II 650W the nearest cheaper option. Native 12V-2x6 cable count is its weakest area, and the SAMA GT650 White covers it better at 1.
Key dimensions & specs
- Wattage: 750W
- Native 12V-2x6 cables: 1
- 80 Plus rating: Gold
- Cybenetics rating: Platinum
- ATX version: ATX 3.1
- Form factor: ATX
- Fan: 135mm
- Fan stop: Yes
- Colour: Black
Pros
- A 750W rating
- A native 12V-2x6 cable for 16-pin cards
- ATX 3.1 compliance
- A fan that stops at low load
Cons
- No published warranty
- Costs more than the Thermaltake Smart BM3 650W at the time of writing
How We Chose
Each pick was assessed across 4 criteria weighted for real-world use.
- The figures behind the order
- We compared four power supplies on rated output, native 12V-2x6 cable count, warranty and 80 Plus rating, using each maker's published specs. We did not test them in-house.
- The shared baseline
- All 4, from the Thermaltake Smart BM3 650W to the Seasonic Focus GX-750, state rated output, ATX version and form factor and share ATX 3.1 ATX version and fan stop.
- Where the specs have gaps
- The Thermaltake Smart BM3 650W gives no native 12V-2x6 cable count; the SAMA GT650 White and the Seasonic Focus GX-750 give no warranty.
- Price range
- At our last check the picks ran from the Thermaltake Smart BM3 650W ($50 to $100) to the Seasonic Focus GX-750 ($150 to $250).
What to Look for in a PSUs for Home Office PCs
Key buying criteria so you get the right fit the first time.
Rated output
Here rated output runs from 650W on the MONTECH Century II 650W to 750W on the Seasonic Focus GX-750. The Seasonic Focus GX-750 is the pick for rated output.
How much warranty you need
Here warranty runs from 5 years on the Thermaltake Smart BM3 650W to 10 years on the MONTECH Century II 650W. Start with the MONTECH Century II 650W if warranty decides it. No figure for the SAMA GT650 White and the Seasonic Focus GX-750.
Cabling
The Thermaltake Smart BM3 650W lists Semi-modular; the SAMA GT650 White and the MONTECH Century II 650W list Fully modular. Settle this first, then compare prices.
Setup checks
The Thermaltake Smart BM3 650W has no stated native 12V-2x6 cable; confirm the cable kit before pairing it with a 16-pin card. The SAMA GT650 White comes with a native 12V-2x6 cable, so a 16-pin card plugs in without an adapter.
Features beyond the spec table
The SAMA GT650 White: embossed white cables. The MONTECH Century II 650W: a 135mm fan with a zero-RPM mode. The Seasonic Focus GX-750: Seasonic's OptiSink design.
How to Choose a PSUs for Home Office PCs
By priority
| Priority | Consider | Why |
|---|---|---|
| Spending as little as possible | Thermaltake Smart BM3 650W | A lower price than the SAMA GT650 White and the rest when we checked |
| Buyers who want ECO silent mode for low-load quiet | SAMA GT650 White | An ECO silent mode for low-load quiet |
| Buyers who want 10-year warranty at a low price | MONTECH Century II 650W | A 10-year warranty at a low price |
| Buyers who put rated output first | Seasonic Focus GX-750 | The highest rated output here (750W) |
Scroll sideways to see every column.
Key specs side by side
The Seasonic Focus GX-750 leads on rated output at 750W, ahead of the Thermaltake Smart BM3 650W at 650W. "Not listed" means the maker leaves that figure out.
| Power supplie | Wattage | Native 12V-2x6 cables | Warranty | 80 Plus rating |
|---|---|---|---|---|
| Thermaltake Smart BM3 650W | 650W | Not listed | 5 years | Bronze |
| SAMA GT650 White | 650W | 1 | Not listed | Not listed |
| MONTECH Century II 650W | 650W | 1 | 10 years | Gold |
| Seasonic Focus GX-750 | 750W | 1 | Not listed | Gold |
Scroll sideways to see every column.
By price at the time of writing
The Thermaltake Smart BM3 650W was the lowest-priced pick and the Seasonic Focus GX-750 the highest when we checked; tiers move with Amazon pricing.
| Price tier | Power supplies |
|---|---|
| About $50 to $100 | Thermaltake Smart BM3 650W, SAMA GT650 White, MONTECH Century II 650W |
| About $150 to $250 | Seasonic Focus GX-750 |
Frequently Asked Questions
How does the Thermaltake Smart BM3 650W compare with the Seasonic Focus GX-750 on rated output?
The Seasonic Focus GX-750 leads at 750W, with the Thermaltake Smart BM3 650W at 650W.
Is the MONTECH Century II 650W ahead of the Thermaltake Smart BM3 650W on warranty?
The MONTECH Century II 650W leads at 10 years, with the Thermaltake Smart BM3 650W at 5 years. The SAMA GT650 White and the Seasonic Focus GX-750 don't state a figure, so they sit outside this comparison.
Is the Seasonic Focus GX-750 worth paying more than the Thermaltake Smart BM3 650W?
On paper it adds rated output (750W against 650W). The Thermaltake Smart BM3 650W was the lowest-priced pick when we checked, so pay the difference only if those gains matter to you.
What makes the Seasonic Focus GX-750 the Highest Rated Output?
It earns the label for the highest rated output here (750W). It suits anyone who put rated output first.
Do the Thermaltake Smart BM3 650W and the MONTECH Century II 650W differ on 80 Plus rating?
The Thermaltake Smart BM3 650W uses bronze; the MONTECH Century II 650W and the Seasonic Focus GX-750 use Gold. The maker of the SAMA GT650 White doesn't say.
What should I check before buying the SAMA GT650 White?
The SAMA GT650 White comes with a native 12V-2x6 cable, so a 16-pin card plugs in without an adapter. No depth is rated for the SAMA GT650 White, so check the maker's page against your case's PSU bay. In this guide it ranks second of 4.
Bottom Line
Our first pick is the Thermaltake Smart BM3 650W, chosen for a lower price than the SAMA GT650 White and the rest when we checked. Look at the SAMA GT650 White for an ECO silent mode for low-load quiet, the MONTECH Century II 650W for a 10-year warranty at a low price and the Seasonic Focus GX-750 for the highest rated output here (750W) if those matter more to you.
Size the wattage to your parts; a larger unit than needed does not help.