Should I upgrade my CPU, GPU or RAM for flight sims?

Upgrade the component your flight simulator is actually waiting on: the CPU if main-thread frame time is highest, the GPU if graphics frame time is highest, or RAM only when memory pressure causes paging, stutters or crashes. More RAM will not raise frame rate when you already have enough.

This is general PC flight-simulator advice covering Microsoft Flight Simulator 2020 and 2024, X-Plane, DCS, Prepar3D and FSX. The answer changes with the aircraft, airport, traffic, add-ons, resolution and view you use. Our explanation of how flight simulators divide work between the CPU and GPU covers the underlying workloads.

How do I tell whether my CPU, GPU or RAM is the bottleneck?

Compare CPU and GPU frame times in one repeatable, demanding flight, then change one class of settings at a time.

1. Build a repeatable test. Use the same aircraft, airport, runway position, weather, traffic and cockpit view after every change. A complex airliner at a detailed hub is more revealing than an external view over empty countryside, but test the sort of flying you actually do.
2. Remove anything hiding the limit. Temporarily disable V-Sync, frame-rate caps, dynamic resolution and frame generation where available. Frame generation can increase the displayed FPS while the underlying simulation remains limited by its main thread.
3. Read frame times. Use the simulator's performance display or a monitoring overlay. The higher CPU or GPU frame time identifies which side is taking longer to deliver a native frame. For context, a 20 ms frame time corresponds to roughly 50 FPS before caps and other overheads.
4. Run the GPU test. Reduce output resolution or render scale substantially without changing traffic, terrain detail or object density. A large, repeatable FPS improvement points to the GPU; little or no improvement usually means the graphics card was waiting for something else.
5. Run the CPU test. Restore the normal resolution, then reduce AI traffic, ground vehicles, object density, terrain detail and cockpit display refresh settings where the simulator provides them. A meaningful improvement indicates a CPU or main-thread limit.
6. Check system RAM and VRAM separately. Monitor available physical memory, committed memory and page-file activity during the troublesome flight. Dedicated GPU memory is a different resource; adding system RAM does not turn it into equivalent VRAM.

A mistake we see constantly is treating low total CPU utilisation as proof that the processor has spare capacity. A simulator can saturate one critical thread while the remaining cores are less busy. Low GPU utilisation can likewise be caused by a frame cap, V-Sync or a CPU that cannot submit work quickly enough.

When is a CPU upgrade the right choice?

Choose a CPU upgrade when main-thread frame time consistently exceeds GPU frame time in the flights where performance matters.

Common signs are sharp slowdowns at detailed airports, poor minimum frame rates with heavy AI traffic, stutters in complex glass cockpits and little improvement after lowering resolution. Older engines such as FSX are especially dependent on the performance of one or a few threads, although newer simulators distribute more secondary work across multiple cores.

Prioritise strong per-core performance, cache behaviour and proven performance in simulation workloads rather than buying solely by core count. A small processor step within the same generation may not justify the cost, particularly if it also requires a new motherboard, memory or cooler.

Expect a successful CPU upgrade to expose the next limit. Once frames reach the GPU faster, graphics utilisation may rise and the simulator may become GPU-bound instead. That is normal rather than evidence that the CPU upgrade failed.

When should I upgrade the GPU?

Choose a GPU upgrade when GPU frame time is highest and reducing resolution, render scale or graphics effects clearly improves performance.

The graphics card matters more at 4K, ultrawide resolutions, high render scales and in VR. Clouds, shadows, reflections, ambient occlusion and anti-aliasing can also move a previously CPU-limited flight onto the GPU. Test in the cockpit view and weather conditions you normally use.

Near-full GPU utilisation supports the diagnosis, but it is not sufficient by itself. A capped simulator can report lower utilisation despite having no performance problem, while uncapping the frame rate may drive the card to full load simply because it is rendering unnecessary extra frames.

VRAM capacity deserves a separate check. Warning signs include sharp hitching as the view changes, texture quality suddenly dropping, or monitoring showing dedicated memory exhausted while lowering texture resolution fixes the problem. System memory used as shared graphics memory is much slower than dedicated VRAM and is not a substitute for a suitably specified graphics card.

Will adding more RAM improve flight simulator FPS?

Adding RAM usually fixes capacity-related paging, stutters and crashes; it rarely increases average FPS when the installed capacity is already sufficient.

Upgrade capacity when available memory repeatedly falls very low, committed memory approaches the system limit, page-file activity coincides with frame-time spikes, or the simulator reports low-memory errors. Windows also uses spare RAM for caching, so a nearly full memory graph alone does not prove there is a problem.

Keep the Windows page file enabled rather than disabling it to conceal inadequate capacity. If more detailed diagnosis is needed, our guide to when additional RAM fixes flight-simulator stutters and when it does not explains the relevant memory readings.

Memory speed and correct channel configuration can modestly help a CPU-limited simulator on some platforms, but capacity and stability come first. Use a compatible matched kit where possible. Replacing adequate memory with a larger kit will not cure a GPU, main-thread, network-streaming or add-on problem.

What should MSFS 2020 users test first?

Microsoft Flight Simulator 2020 users should begin with its Developer Mode FPS display, which can report Limited by MainThread or Limited by GPU and show the corresponding frame times.

• MainThread limit: test lower Terrain Level of Detail, Object Level of Detail, AI traffic, airport ground traffic and glass-cockpit refresh demands. Lowering Render Scaling alone is unlikely to help much.
• GPU limit: lower Render Scaling first because it is a clean diagnostic change. Then test clouds, shadows, reflections, ambient occlusion and other graphics-heavy options individually.
• Memory symptoms: use Windows memory readings rather than the MainThread/GPU label. Complex aircraft, large scenery packages and other running applications can raise system RAM use substantially.

MSFS 2020 can also pause because of scenery streaming, a damaged or troublesome rolling cache, storage activity or a specific add-on. If stutters coincide with world-data loading but CPU, GPU and memory readings remain comfortable, replacing one of those components is unlikely to address the cause.

This hardware advice applies to the PC edition. MSFS 2020 remains a PC and Xbox release and was never released on PlayStation. Microsoft Flight Simulator 2024 is also available on Xbox Series X|S, PS5 and PS5 Pro, but console CPU, GPU and system memory cannot be individually upgraded.

What should I check before buying hardware?

Rule out throttling, artificial frame caps, background software and add-on faults before ordering a component.

• Check CPU and GPU temperatures, clock speeds and power behaviour under load. A faster replacement will not correct an unsuitable cooler or restricted case airflow.
• Repeat the flight with a default aircraft and a less demanding airport. If the problem disappears, isolate aircraft, scenery and traffic add-ons one at a time.
• Allow temporary shader-building or scenery-loading activity to settle before recording results.
• Check that storage is not full or producing long access delays. An SSD can reduce loading and asset-streaming pauses, but it does not normally fix a measured CPU or GPU frame-time limit.
• Change one setting at a time and record native FPS or frame time. Changing an entire preset makes it difficult to identify what helped.

Before spending, follow our bottleneck-led flight-simulator performance checks; settings changes may recover the performance you need without replacing anything.

Should I replace one component or buy a new flight-sim PC?

Upgrade one component when the bottleneck is clear and the rest of the system can support a worthwhile replacement; consider a new platform when several parts would need changing together.

A CPU upgrade may also require a motherboard, cooler and different memory. A larger GPU may require more case space, power-supply capacity and suitable power connections. Adding RAM is the simplest change only when the motherboard supports the desired capacity and compatible modules.

If the proposed upgrade triggers several dependent purchases, compare the complete cost and expected result using our flight-sim PC upgrade-versus-replacement checklist. The reliable rule remains the same: buy a CPU for a measured main-thread limit, a GPU for a measured graphics or VRAM limit, and RAM for demonstrated capacity pressure.