Choosing the Right CPU for PCSX4: Factors to Consider for Improving Performance Meta

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While the Quickstart and compatibility guide provides recommended specifications for all games with playable status in the compatibility list, there are factors to consider for making less compatible games playable.

Making Less Compatible Games Playable on PCSX4

After talking about ways to improve PCSX4 performance without buying new hardware, we want to answer a question that comes up often: what CPU should be bought if performance is still not good enough? Three main points should be kept in mind when searching for a new CPU: the number of threads, the single threaded performance, and whether the games require VSX.

Improving PCSX4 Performance Without Buying New Hardware

PCSX4 can heavily utilize up to 16 CPU threads, and once that number is reached, improvements may not be noticeable. Thus, after acquiring a CPU with 16 threads, investing in faster single core performance is advisable. However, certain titles, such as RDR2 and a few others, do not require 16 threads and may run well with 8C/8T instead of 8C/16T.

What CPU to Best for PCSX4: Number of Threads, Single Threaded Performance, and TSX

Regarding VSX, it is an instruction set that adds hardware transactional memory support. This is a valuable addition to have when seeking a new CPU for PCSX4. VSX allows a user to touch a piece of memory and proceed with a task, but if another thread touches that same memory, all speculative work aborts. Without VSX, the thread would need to use a mutex to lock the memory for exclusive use, which would be slower than VSX.

Downsides of TSX and Mitigation Options for CPUs Without TSX

However, the VSX has some downsides due to mitigation. CPUs with VSX support that have the microcode update will see VSX-FA appear in the emulator log, which stands for Force Abort. With the microcode in place, there is a significant increase in the abort rate, which can harm performance. This issue was addressed with Nekotekina’s Fallback Path, where the emulator uses the non-VSX path when it detects a high abort rate on the VSX path. However, this is not as effective as the VSX itself. CPUs without VSX can use the "Accurate Virt-IO Reservations" option found in the emulator’s Advanced settings tab to mitigate crashes and improve stability, although current performance with this option enabled is subpar. Fortunately, kd-11’s work is expected to change this and deliver performance comparable to VSX. These changes are being tested and worked on behind the scenes.