This article covers 「SeaSonic SS-300TFX 」スリムPC用300W電源 TFX電源 SATA 24pin.

Overview

The SeaSonic SS-300TFX is a 300W power supply designed in the compact TFX form factor for slim desktop PCs and space-constrained builds. It carries 80 PLUS Bronze certification, ensuring efficient power conversion with lower heat output. This unit is ideal for office PCs, home servers, and media-center systems where reliability and compact size matter more than raw performance. Seasonic’s reputation for stable, long-lasting PSUs makes this a safe choice for budget-conscious builds.

Compatibility Guide

This PSU strictly follows the TFX form factor, meaning it only fits cases designed for TFX power supplies—standard ATX cases cannot accommodate it. It complies with Intel TFX 12V v2.31 and includes a 20+4 pin main power connector and a 4-pin CPU (P4) connector. SATA connectors are provided for drives and peripherals. With a 300W capacity, the SS-300TFX can handle systems with integrated graphics or low-power discrete GPUs (up to 75W TDP). Always verify your chassis supports TFX before purchasing.

Product Info

The SS-300TFX has been a staple in Seasonic’s TFX lineup, offering 80 PLUS Bronze efficiency for years. It uses an 80mm double ball-bearing fan for quiet operation and includes comprehensive protection: short-circuit (SCP) and over-current (OCP) on all outputs. Market positioning is entry to mid-range for slim PCs—prioritizing reliability and size over peak performance. The unit lacks modern features like a 12VHPWR connector or fully modular cabling, but its straightforward design fits its intended use case well.

Best Use Cases

First, this PSU is perfect for building or upgrading a slim desktop PC, especially in Mini-ITX or STX cases that require a TFX power source. Second, it suits low-power home servers or NAS systems where 24/7 operation demands high efficiency and low heat. Third, it’s a solid drop-in replacement for aging OEM TFX units in office desktops, thanks to Seasonic’s proven reliability. In all scenarios, the SS-300TFX provides stable power without unnecessary bulk. ## Alternatives
Competing TFX options include units from FSP and Delta, but the SS-300TFX stands out with its 80 PLUS Bronze certification—most FSP TFX 300W models lack any efficiency rating. Delta’s offerings are often geared toward enterprise builds and are harder to source for consumers. If you need a bit more headroom, Seasonic’s own SS-350TGM (350W, Gold) is a step up, but for strictly budget TFX builds, the SS-300TFX remains a value leader.

Things to Consider

The biggest limitation is the TFX form factor—double-check your case supports it. The 300W capacity severely restricts GPU choice; only integrated graphics or sub-75W cards (e.g., GT 1030) are viable. This model lacks a 12VHPWR connector and is not modular, so cable management inside tight cases can be tricky. Additionally, the SS-300TFX is an older design; if you require higher efficiency (e.g., Gold or Platinum) or want a fully modular unit, you should look at newer Seasonic TFX offerings. For basic slim builds, however, it remains a reliable, affordable option.

Product Disclosure (Amazon)

  • Manufacturer: Seasonic
  • Seller: VIA AIR
  • Fulfilled by: VIA AIR
  • ASIN: B004JUVNVC
  • Note: This article covers a manufacturer-made product based on Amazon listing details.