The PSU bill includes cables, fit and replacement risk
Start with the exact GPU’s system-power recommendation, then check the CPU and included cables. A larger wattage does not resolve a missing connector, incompatible modular cable or PSU that cannot fit beside the drive cage.
Check
Document to use
Decision
GPU connection
Card manual plus PSU cable inventory
Count separate required cables, not just plugs on one lead
Electrical behaviour
Independent test of exact wattage and revision
Efficiency certification alone does not establish noise or transient response
Old modular PSU replacement
New PSU compatibility documentation
Replace old modular cables unless explicitly compatible
Put efficiency savings in dollars
At a hypothetical 400 W DC load, 90% efficiency draws about 444 W from the wall; 92% draws about 435 W. The difference is roughly 9.7 W. At 4 hours a day and an assumed C$0.10/kWh, that is about C$1.41 a year. This is a calculation, not a measurement of the listed PSUs or a current electricity tariff. Pay extra for a better unit when the whole package merits it, not on an exaggerated savings claim.
SIZING · 2026
What capacity should you choose for each GPU?
The official recommendation is a reference-system starting point. The practical range adds sensible headroom for a demanding CPU, higher-power partner card, transients and aging—without turning every PC into a 1,300 W build.
GPU
Reference minimum
Practical range
RTX 5070 / RX 9070
650 W
650–750 W
RTX 5070 Ti / RX 9070 XT
750 W
750–850 W
RTX 5080
850 W
850–1,000 W
RTX 5090
1,000 W
1,000–1,300 W
ATX 3.0, ATX 3.1 and 12V-2x6
A current ATX 3.x PSU is designed to better handle fast modern-GPU transients. For a 12V-2x6 card, prefer a native cable supplied with the unit, fully seat it and leave room before the first bend. Never reuse a modular cable from another model.
Oversize only when the CPU, overclock, multiple GPUs, sustained load or a planned upgrade justifies it. Otherwise, pay for a better platform, complete protections and a long warranty.
Exact modelVerify GPU, CPU and power limit.
CablesCount native PCIe, EPS and 12V-2x6.
QualityReview protections, warranty and independent testing.
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RTX 5070 · 850 W
RTX 5080 · 1,000 W
RTX 5090 · 1,300 W
DUAL GPU · 1,600 W