Build a Gaming PC — Parts and Setup Checks

PSU Wattage, Bottleneck, Monitor PPI, FOV and Mouse Sensitivity Calculators

When you build a gaming PC, the parts list is only half the job. The power supply has to cover the graphics card's spikes, the CPU and GPU should be matched, and the monitor and mouse need setting up so aim feels right. These six calculators cover it in order.

The tools, in order

  1. PSU Wattage Calculator

    Add up the parts and size the power supply with headroom for spikes.

  2. PC Bottleneck Calculator

    Check the CPU and graphics card are a sensible pair at the resolution you play at.

  3. Monitor PPI Calculator

    Compare monitor sizes and resolutions by pixel density before you buy the screen.

  4. FOV Calculator

    Set a field of view that matches your screen size and seating distance.

  5. EDPI Calculator

    Turn mouse DPI and in-game sensitivity into one number you can compare.

  6. Cm/360 Calculator

    Measure how far the mouse travels for a full turn, and keep it the same across games.

What to check first when you build a gaming PC

Start with power, because a power supply that is too small causes crashes that look like faulty parts. Modern graphics cards draw short spikes well above their rated board power, so size the supply with a margin over the total rather than to the exact sum. A good quality unit at a sensible wattage beats a bigger cheap one.

Matching the CPU and graphics card

A bottleneck is not a fault, it is just the part that limits frame rate. At 1080p the processor limits more often; at 1440p and 4K the graphics card usually does. Spend most of the budget on the part that limits you at the resolution and refresh rate you actually play at, rather than on balance for its own sake.

Setting up the screen and mouse

Pixel density decides how sharp a monitor looks at your seating distance, so compare it rather than resolution alone. Then match field of view to the real angle the screen fills, and settle on one sensitivity. Measuring in centimetres per 360 degree turn lets you carry the same aim from one game to the next.

FAQ

How many watts does my gaming PC need?

Add the graphics card and processor power figures, plus a smaller allowance for the motherboard, drives, fans and lighting, then leave headroom on top for transient spikes. The PSU calculator does this sum and suggests a sensible wattage for the parts you enter.

Is a CPU bottleneck bad?

Every system has a bottleneck, so the question is only whether it limits you at the settings you use. If frame rate is already above your monitor's refresh rate, the bottleneck does not matter. If it falls short, upgrade the part that is holding back that particular game.

What is a good eDPI for shooters?

Most competitive players in tactical shooters sit at fairly low eDPI so they aim with the arm rather than the wrist. There is no single right number, so start from what feels controlled, then adjust in small steps and keep the same centimetres per turn across games.