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Setting Up CPU Affinity & Process Priority | ASM v0.8.3

CPU Affinity & Process Priority

Pin your server to specific cores (ASM v0.8.3)

By default, Windows is free to bounce ARK across any CPU core it likes — which causes stutter, especially when you run more than one server on the same machine. ASM's CPU Settings dialog lets you pin each server to specific cores and bump its process priority, so heavy servers get consistent CPU time and lighter ones don't fight them for cycles.

CPU Settings are per-server and persist across restarts. ASM re-applies them whenever it spawns or detects the ARK process.

Find the CPU Settings Button

On the dashboard, look at the top-right corner of each server's card. You'll see two small icons: the CPU Settings icon (a small processor chip) and the menu icon (three dots). Hover the CPU icon and you'll see the tooltip "CPU Settings" — or "CPU Settings (Active)" if you've already configured affinity for this server.

Dashboard with the server card showing the CPU Settings icon in the top-right corner

Close-up of just the CPU Settings icon button:

CPU Settings icon button close-up from the dashboard card

The icon turns green with a soft glow when CPU settings are active for that server — quick visual confirmation that something is pinned.

Open the CPU Settings Dialog

Click the icon. The CPU Settings — <Your Server> dialog opens, showing two sections: CPU Priority at the top and CPU Affinity below it. The dialog auto-detects every logical core on your CPU and renders them as a grid of checkboxes (24 cores in the screenshot below; yours may show fewer or more).

CPU Settings dialog showing the Priority Level dropdown and the Core checkbox grid

Pick Which Cores the Server Can Use

In the CPU Affinity section, tick the checkboxes for the cores you want this server to run on. Common patterns:

A Single server, dedicated machine: leave all cores ticked (or use SELECT ALL) so Windows is free to schedule wherever it wants. ASM treats "all selected" the same as "no affinity set" — you can also just click CLEAR ALL to use the default.
B Two servers, same machine, want them isolated: give Server 1 the first half (cores 0–11 on a 24-thread CPU), Server 2 the second half (cores 12–23). Each gets a dedicated lane and they can't fight.
C One heavy server, multiple lighter ones: give the heavy one the high-numbered cores (often the high-clock cores on modern CPUs), share the lighter ones across the rest.
D Reserve cores for the OS / background tasks: unselect cores 0 and 1 across all ARK servers — leaves Windows breathing room for SteamCMD, backups, and your own desktop work.

Don't pin a single server to just one core. ARK is multi-threaded internally; restricting it to one core will halve frametime performance. Two cores minimum, four to eight is a sensible starting point for most servers.

Set the Process Priority

The CPU Priority section at the top of the dialog has a single dropdown labelled Priority Level. The default is Normal, which is fine for most setups. The four available levels and when to use them:

Priority When to use
Low Test / dev / dormant servers that you want to keep running but never compete with anything else for CPU.
Normal Default. Use this unless you have a specific reason to change it — Windows balances ARK against everything else fairly.
High Production server on a dedicated host where you want ARK to win every time the OS schedules. Safe on modern hardware with the OS pinned to its own cores.
Realtime Use with extreme caution. ARK pre-empts everything including disk I/O and network drivers. Can make the whole machine unresponsive if ARK pegs the CPU. Only consider if you've tested it on identical hardware and have a hardware reset button handy.

Higher priority doesn't make ARK faster on its own. It just shifts which process wins the CPU when multiple things want it. If ARK has free CPU available, it'll already use as much as it needs at Normal priority.

Save & Apply

Click the blue SAVE & APPLY button in the bottom-right of the dialog. ASM does two things:

1 Persists the settings to data\cpu_settings.json so they survive ASM restarts.
2 Applies immediately if the server is running — ASM finds the ARK process and updates its affinity / priority on the fly. If the server is stopped, the settings apply on next start.

The icon on the dashboard card turns green to confirm CPU settings are now active for this server.

When CPU Affinity Actually Helps

CPU affinity is genuinely useful for some setups and a wasted tweak for others. Honest summary:

Multiple ARK servers on one machine — biggest impact. Isolating them stops cross-server stutter caused by both servers grabbing the same cores at the same time (auto-saves, mod loads).
Mixed CPU with P-cores and E-cores (Intel 12th-gen+, AMD X3D) — pin ARK to the performance cores (usually 0–7 or 0–15) and let the OS use the efficiency cores. Modest but measurable.
Server-and-desktop on the same box — reserve a couple of cores for your desktop work + browser + Discord, give the rest to ARK.
Single ARK server on a dedicated box — usually not worth setting. Windows already schedules ARK fine. Leave it alone unless you've measured stutter.
Low player counts (under 20) — ARK barely uses CPU. Affinity tweaks rarely show up in player-facing performance.

CPU Settings Saved!

Your server now runs on its dedicated cores at the priority you picked. Open Task Manager → Details → right-click ArkAscendedServer.exe → Set affinity to verify the cores actually applied.

Related Guides

Custom Console Arguments

Fine-tune the ARK process

View Guide
Automated Backups

Schedule backups + restores

View Guide
Firewall Setup

Open the required ports

View Guide