Quick Answer
A 1500W unit gives a RTX 4080 Super real overclocking headroom: the system sits near 32% load in games, leaving plenty of rail for a power-limit increase. The card's 320W board power and the roughly 475W full-system draw are the numbers to plan around. Raising the GPU power limit 10-15% adds maybe 32-48W, so size the supply for the spike, not the average.
Headroom maths for a 1500W RTX 4080 Super
Start from steady draw. The RTX 4080 Super pulls about 320W, a 6-8 core CPU adds 120-150W under load, and the rest of the platform 60-80W, for roughly 475W total. On a 1500W supply that is about 32% load. The useful headroom for overclocking is whatever sits above that: a 10-15% GPU power-limit bump adds 32-48W, and a CPU all-core tune another 30-50W, so you want to stay clear of sustained 90%-plus load to keep the unit cool and quiet.
Overclocking the RTX 4080 Super sensibly
These Ada/Blackwell cards respond better to power-limit and memory tuning than to raw core offsets. Push the power slider in MSI Afterburner first, watch the effective clock and temperatures, then add a small core offset and a memory step if it stays stable in a 30-minute loop. The RTX 4080 Super feeds through a 12VHPWR / 3x 8-pin adapter; on an ATX 3.1 1500W unit the transient spikes from an overclock are handled natively, which is exactly why headroom on the supply translates into stable boost clocks rather than random shutdowns.
SA buying notes
For overclocking headroom, the supply quality matters as much as the wattage. Evetech stocks Corsair RM/RMx, Seasonic Focus/Vertex and MSI MPG units in the 1500W Gold class with ATX 3.1 cabling; the current price band is on each product page. A reviewed unit holds its rated output at SA's warm ambient temperatures, where a cheap supply sags under sustained load and undoes any overclock you dial in.
FAQ
How much overclocking headroom does 1500W give a RTX 4080 Super?
A 1500W unit gives a RTX 4080 Super real overclocking headroom. Expect a usable 10-15% GPU power-limit increase plus a light CPU tune before load climbs uncomfortably. Beyond that, the 850W class is the relaxed choice.
Will an overclock trip a 1500W PSU?
Not on a quality ATX 3.1 unit at this wattage; it handles the extra 32-48W and the transient spikes natively. A cheap or under-rated supply is what trips, which is why the brand matters more than the headline wattage.
Is a bigger PSU worth it just for overclocking?
Only to a point. A 1500W supply already gives this card room; jumping far above it mainly buys efficiency at idle and a future-upgrade buffer, not more clock speed.
OC starting point
Raise the GPU power limit first in MSI Afterburner, confirm stability in a 30-minute loop, then add a small core and memory offset; on a 1500W ATX 3.1 unit a RTX 4080 Super has the rail to hold the boost clock.