Optimal RAM for All the Mods 9 (ATM9) & JVM Optimization Guide
One of the largest modern modpacks, combining expansive technical machinery (GregTech, Mekanism), complex magical structures, and endless dimensions. ATM9 pushes the Java Virtual Machine to its absolute limits, demanding meticulous memory allocation.
Memory Allocation Map
OS memory is choked. Hard disk pagefile swapping will cause heavy, multi-second gameplay freezing!
Optimized JVM arguments console
Pre-configured garbage collection bounds synchronized to your sizer metrics.
Performs memory cleanup concurrently with game loops. Pause times are consistently below 1ms, completely eliminating garbage-collection lag spikes and visual stutters.
⚙️ Requirements: Requires Java 21+ and a memory pool of 6GB or higher.E.g. You attempted to allocate 9GB of RAM on a 16GB PC.
Because Minecraft runs inside a virtual machine (JVM), the host operating system (Windows/macOS), graphics drivers, Discord, and Chrome require dedicated memory headroom to coordinate background tasks. Allocating more than 50% of system memory triggers intense disk paging (swap files), which freezes frame timings and locks your PC.
💡 Solution: We have safely scaled back your JVM maximum size to 8GB (50% capacity cap).Minecraft Out-of-Memory (OOM) Crash Registry
Common crash signatures that indicate your Java heap allocations are failing.
Occurs when Windows runs completely out of physical system memory and forcibly kills the Java VM. Triggered by over-allocating RAM inside launchers or running out of pagefile space.
Occurs when Minecraft Modpack registries baked items exceed allocated heap size. The internal JVM throws a "Java heap space" exception and shuts down safely. Solve by scaling up allocation slider.
Occurs when the JVM spends more than 98% of CPU time performing garbage collection loops but frees less than 2% of the heap. This causes intense stuttering before crashing. Check JVM arguments.