Optimal RAM for All the Mods 9 (ATM9)
Allocate about 8GB JVM heap for All the Mods 9 (ATM9), on a 16GB+ dual-channel system so Windows is not starved. Prefer Java 21 with Generational ZGC (Java 21); never give Minecraft more than half of physical RAM.
JVM baseline
8 GB
System RAM target
16 GB+
Mod count
410 mods
GC engine
Generational ZGC
Dual-channel kits for 16GB+ systems
Disclosure: As an Amazon Associate I earn from qualifying purchases. Rankings use price and spec data only — not paid placement. How we rank products
Shop physical RAM for the PC hosting All the Mods 9 (ATM9) — not the JVM Xmx value alone. Leave headroom so Windows is not paging while the pack loads.
Best match
Corsair Vengeance LPX 128GB (4x32GB) DDR4 3600 (PC4-28800) C18 1.35V Desktop Memory - Black
$194.99 · $1.52/GB
In stock
DDR5 kit
CORSAIR Vengeance RGB DDR5 RAM 96GB (2x48GB) 6000MHz CL30 Intel XMP iCUE Compatible Computer Memory - Black (CMH96GX5M2B6000C30)
$189.99 · $1.98/GB
In stock
DDR4 kit
CORSAIR Vengeance LPX DDR4 RAM 64GB (2x32GB) 3600MHz CL18-22-22-42 1.35V Intel AMD Desktop Computer Memory - Black (CMK64GX4M2D3600C18)
$149.99 · $2.34/GB
In stock
Memory Allocation Map
OS memory is choked. Pagefile swapping will cause multi-second freezes.
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.
Frequently Asked Questions (FAQ)
What is the absolute maximum RAM I should allocate for ATM9?▼
Can I run ATM9 with only 8GB of total system RAM?▼
Related Minecraft profiles
Next steps
Tune JVM settings above, then shop a dual-channel kit — or dig into stutter causes and platform guides.