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Compact TFX power supply unit with metal casing and 80mm fan grille visible

myVolts

myVolts TFX 420W AT Power Supply 300W Upgrade

SKU CH-6BCC-KAEDT

TFX form-factor AT power supply delivering 420 W steady output to replace 200–350 W units in slimline and SFF desktops

  • Product typeAT
  • Replaces 250–350 W units with 420 W peak power
  • 300 W continuous output for stable daily operation
  • 20+4 pin ATX plus 4-pin CPU for broad motherboard fit
  • Two SATA and two Molex connectors for drives and peripherals
  • 80 mm double-ball-bearing fan keeps temperatures low

TFX 420W AT power supply

This TFX form-factor AT power supply delivers 420 watts of continuous output for slimline and small-form-factor desktops. It replaces Bestec TFX0250P5WB and TFX0250D5W units rated at 200, 250, 300 or 350 watts. The unit accepts 100 to 240 volts AC input and includes a 20+4 pin motherboard connector, 4-pin CPU connector, two Molex, a floppy connector and two SATA connectors.

Installation and common issues

The TFX chassis fits standard slimline bays and uses four mounting screws aligned with the original Bestec pattern. An 80 mm double-ball-bearing fan provides airflow; verify the fan orientation matches your case venting before securing the unit. The 20+4 pin plug separates for older 20-pin boards — do not force the full connector into a 20-pin socket. Route the fixed cables carefully in tight SFF interiors to avoid blocking the fan intake.

Pre-order checklist

Confirm your current PSU is a Bestec TFX0250P5WB or TFX0250D5W revision X2, X3 or X4 so the mounting holes and connector layout match. Check that the motherboard requires a 20+4 pin main power connector and a 4-pin CPU power connector. Ensure the case has clearance for an 80 mm fan exhaust and that the 100 to 240 volt input range suits your local mains supply. Count the SATA, Molex and floppy devices you plan to power against the two SATA, two Molex and one floppy leads provided.

How it compares

Measured against everything we stock in ATX Desktop Power Supplies, at today’s prices. Recalculated every night.

Price $106.99
Cheaper than about 64% of the 10,869 comparable items (median $142.99).

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Specifications

Product
Product typeAT

Questions about this item

How can I verify the 80 mm double ball-bearing fan is spinning after installation?

Listen for the fan and feel airflow at the rear grille once the system powers on; steady rotation confirms the cooling is active.

Which cables come attached and which ones must be sourced separately?

The unit includes a 20+4 pin motherboard connector, a 4-pin CPU connector, two Molex, one floppy and two SATA leads; no extra cables are required for those interfaces.

Should I choose the 300 W or 420 W rating for a system that originally used a 250 W Bestec TFX unit?

The supply delivers up to 420 W, so it covers the original 250 W, 300 W and 320 W versions and provides extra headroom for added peripherals.

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