PSU calculator and bottleneck calculator

Add your GPU's board power to your CPU's peak package power, then add roughly 60 to 100 W for the motherboard, memory, drives and fans. Choose a power supply where that total sits at roughly 65% of its rating on a mid-range build, rising to about 80% on a very high-wattage build, which gives efficiency headroom and absorbs transient spikes.

A CPU bottleneck happens when your processor cannot prepare frames fast enough to keep your graphics card busy, so the GPU sits partly idle. It shows up most at lower resolutions and in simulation-heavy games with dense traffic, crowds and physics.

Not usually. Being GPU-limited means you are already getting everything your processor can deliver, and a graphics card upgrade will translate directly into higher frame rates. It is generally the better of the two situations.

16 GB is the practical floor and 32 GB is the comfortable target for modern open-world games plus background applications. Always run two sticks so memory operates in dual-channel mode.

For any build drawing 850 W or more, yes. ATX 3.x supplies are designed for the large, brief power spikes modern GPUs produce and include a native 12V-2x6 connector, which is safer than using an adapter.

No. A power supply only delivers what the components request, so a 1000 W unit in a 400 W system draws roughly the same from the wall as a 650 W unit would. Oversizing costs money upfront, not on your electricity bill.

Add your graphics card's rated board power to your processor's peak package power, then add roughly 60 to 100 W for the motherboard, memory, drives and fans. Size the supply so that total sits at about 65% of its rating. The calculator above does this from your exact parts.

Rarely. A 750 W unit is sensible headroom for most mid-to-high-end builds and costs nothing extra to run, because a power supply only delivers what the components request. It is only overkill if you never plan to upgrade your graphics card.

For a mid-range build, yes in the sense that you are paying for capacity you will not use — but it does not increase your electricity bill, and it leaves room for a future GPU upgrade. For an RTX 4090 or RTX 5090 build, 1000 W or more is genuinely necessary.

Most gaming PCs need between 550 W and 850 W. An RTX 5060-class build is fine on 550 W, an RTX 5070 or RX 7800 XT wants 650 to 750 W, an RTX 4090 wants 850 to 1050 W, and an RTX 5090 build needs 1200 W or more.

The wattage is printed on a label on the power supply itself, usually facing into the case. No software can read it reliably, so check the label, look up your exact PSU model number, or consult the specification sheet if you have a pre-built system.

No. A power supply only delivers the power the components actually draw, so a 1000 W unit in a 400 W system pulls roughly the same from the wall as a 650 W unit would. Oversizing is an upfront cost, not an ongoing one.

Choose on three things: wattage sized so your system's draw sits near 65% of the rating, an 80 Plus Gold or better efficiency certification from a reputable brand, and ATX 3.x with a native 12V-2x6 connector if your build draws 850 W or more. The calculator above gives you the wattage figure.

Treat any bottleneck calculator — including this one — as a guide rather than a measurement. Real bottlenecks vary by game, resolution and settings: CPU limits dominate at 1080p and in simulation-heavy titles, while GPU limits dominate at 4K. Tier comparisons reliably flag large mismatches, which is what matters when planning a build.

Yes. A quality 750 W power supply comfortably runs an RTX 4080, RTX 5070 Ti or RX 9070 XT alongside a mainstream processor — those cards draw 300–320 W and the vendors recommend exactly 750 W. Pair one with a 200 W-plus Core i9 or Ryzen 9 and 850 W is the safer choice.

It can work, but 850 W is the recommended figure for both. The RTX 4090 draws 450 W and the RTX 5080 draws 360 W, and both produce large transient spikes that can trip an undersized unit's protection even when average draw looks fine. Use 850 W, and make it ATX 3.x.

Nvidia recommends a 1000 W power supply for the RTX 5090, which has a 575 W board power. Use an ATX 3.x unit with a native 12V-2x6 connector rather than an adapter, and step up to 1200 W if you are also running an overclocked Core i9 or Ryzen 9.

650 W is the recommended figure for both. The RTX 4070 draws 200 W and the RTX 5070 draws 250 W, so a good 650 W unit leaves comfortable headroom with a mid-range CPU. There is no need for 750 W unless you plan to upgrade the card later.

550 W is plenty for either. The RTX 4060 draws just 115 W and the RTX 3060 draws 170 W, so even a modest quality unit handles them. A 550 W 80 Plus Bronze or Gold supply from a reputable brand is the sensible buy.

Nvidia recommends 750 W for the RTX 3080, which has a 320 W board power and uses two 8-pin connectors. The RTX 3080 Ti has the same 750 W recommendation at 350 W board power. With a high-end CPU, 850 W gives more comfortable margin.

Add your graphics card's board power to your processor's peak package power, then add roughly 60 to 100 W for the motherboard, memory, drives and fans, and size the supply so that total sits near 65% of its rating. Most gaming PCs land between 550 W and 850 W. The calculator above works it out from your exact parts.

Look up your PC model's specification sheet if it is a pre-built, or check the original invoice if it is a custom build — the PSU model number usually contains the wattage. No monitoring software can read a power supply's rated capacity, because most units have no sensor the operating system can query.

No. Tools like HWiNFO, Speccy, CPU-Z and Task Manager cannot report your power supply's rated wattage; it is not a sensor Windows can read on a standard unit. Only high-end digital PSUs such as the Corsair AXi and HXi series report live power draw, and even then that is consumption rather than rated capacity.

No. A power supply delivers only what the components actually request, so a 1000 W unit in a 400 W system draws roughly the same from the wall as a 650 W unit would. Oversizing costs money at purchase, not on your electricity bill.

For any build drawing 850 W or more, yes. ATX 3.x units are designed for the large, brief power excursions modern GPUs produce and include a native 12V-2x6 connector, which is safer and tidier than running an adapter from multiple 8-pin cables.

Usually the system shuts down or reboots abruptly under load — most often mid-game, when the GPU spikes. You may also see crashes, black screens or failure to POST. An underpowered supply is not just an inconvenience; a low-quality unit failing under strain can damage other components.