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Standard ATX power supply unit with single fan and matte metal finish

Replace Power

Replace Power RPMPS3420-7 400W ATX power supply

SKU CH-7237-31TCA MPN RPMPS3420-7

400 W ATX power supply replaces Bestec 0950-4107, ATX-1956D and ATX-300-12Z-CDR units with 20+4-pin and +12 V connectors, single-rail design and 115/230 V input

  • TypeATX
  • Fans1
  • Weight0.1
  • Delivers 400W continuous power for stable desktop operation
  • Single 12V rail supplies 16A for modern component compatibility
  • 20+4 pin main connector fits both 20-pin and 24-pin motherboards
  • Manual 115/230V input switch supports worldwide mains voltages
  • Replaces Bestec 0950-4107 and ATX-300-12Z-CDR units directly

400 W ATX replacement unit

This Replace Power RPMPS3420-7 is a 400 W ATX power supply designed to replace Bestec 0950-4107 ATX-1956D ATX-300-12Z-CDR units in older desktop PCs. It delivers power through a single-rail design with a 20+4-pin main connector and standard peripheral leads. One built-in fan provides cooling.

Suits owners of compatible legacy systems

It suits owners of Dell, HP or other desktops that originally shipped with the listed Bestec models and need a direct swap. Builders assembling new systems, or anyone requiring modular cables, higher wattage or modern efficiency ratings, should look elsewhere.

400 W total output with single +12 V rail

The unit supplies +12 V at 16 A, +3.3 V at 13 A and +5 V at 13 A, with -12 V at 0.8 A, -5 V at 0.5 A and +5 VSB at 2.5 A. Hold-up time is 17 ms minimum and rise time is under 70 ms. It will run out of headroom on builds that demand more than the rated 400 W or multiple high-current +12 V devices.

Highlights

  • Delivers 400W continuous power for stable desktop operation
  • Single 12V rail supplies 16A for modern component compatibility
  • 20+4 pin main connector fits both 20-pin and 24-pin motherboards
  • Manual 115/230V input switch supports worldwide mains voltages
  • Replaces Bestec 0950-4107 and ATX-300-12Z-CDR units directly

Specifications

BrandReplace Power
ModelRPMPS3420-7
TypeATX
Fans1
Weight0.1

Questions about this item

What existing case and motherboard connectors does this 400W ATX unit need to fit and power the system?

It requires a standard ATX mounting opening and a motherboard with a 20+4 pin main connector plus a +12V auxiliary plug.

Will the single 12V rail delivering 16A support older components that expect split 12V rails?

Yes, the single +12V rail at 16A combines the current that older multi-rail designs separated, so legacy parts draw from the same pool.

How can I verify the supply is operating correctly once installed?

Measure the +3.3V, +5V and +12V outputs under load; they should stay within ATX tolerance, and the power-good signal must assert within 70 ms with at least 17 ms hold-up after AC loss.

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