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Minecraft ModpackJava 21

Optimal RAM for Cobblemon

Allocate about 4GB JVM heap for Cobblemon, on a 16GB+ dual-channel system so Windows is not starved. Prefer Java 21 with tuned G1GC; never give Minecraft more than half of physical RAM.

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JVM baseline

4 GB

System RAM target

16 GB+

Mod count

40 mods

GC engine

Optimized G1GC

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 Cobblemon — 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

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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

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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

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40 Mods
Vanilla (0)Small (50)Medium (150)Heavy (300)Extreme (450+)
12 Chunks
Short (4)Normal (12)Far (18)Extreme (32)

Memory Allocation Map

4GB JVM
12GB OS
allocated to JVM Free for Windows
Recommended allocation4 GB
Garbage CollectorG1GC
JVM Stutter / Pause Risk
LOW

Light heaps keep G1GC sweeps short without heavy stutters.

Minecraft Modpack presetJava 21 runtime

Optimized JVM arguments console

Pre-configured garbage collection bounds synchronized to your sizer metrics.

-Xms4G -Xmx4G -XX:+UseG1GC -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 -XX:+UnlockExperimentalVMOptions -XX:+DisableExplicitGC -XX:+AlwaysPreTouch -XX:G1NewSizePercent=30 -XX:G1MaxNewSizePercent=40 -XX:G1HeapRegionSize=8M -XX:G1ReservePercent=20 -XX:G1HeapWastePercent=5 -XX:G1MixedGCCountTarget=4 -XX:InitiatingHeapOccupancyPercent=15 -XX:G1MixedGCLiveThresholdPercent=90 -XX:G1RSetUpdatingPauseTimePercent=5 -XX:SurvivorRatio=32 -XX:+PerfDisableSharedMem -XX:MaxTenuringThreshold=1
Optimized G1GC (Garbage-First Collector)

Uses highly tuned sizing percentages and short garbage collection windows (MaxGCPauseMillis=200). Works perfectly for legacy clients or memory pools under 6GB.

⚙️ Requirements: Compatible with Java 8, 17, and 21. Optimal for low-overhead setups.

Minecraft Out-of-Memory (OOM) Crash Registry

Common crash signatures that indicate your Java heap allocations are failing.

Exit Code -1073740791System Starvation Crash

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.

OutOfMemoryErrorJVM Heap Exhaustion

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.

GC Overhead Limit ExceededGarbage Collection Thrashing

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)

How much RAM for Cobblemon?▼
4GB JVM is enough for a lean Cobblemon Fabric client. Use 6GB if you stack Create/tech mods or HD packs. Keep total system RAM at 16GB dual-channel minimum.
Does Cobblemon need Java 21?▼
Modern Cobblemon targets current Minecraft versions that run best on Java 21. Use the pack's recommended runtime and avoid oversized heaps on 8GB laptops.

Related Minecraft profiles

GregTech New Horizons (GTNH)Better MinecraftCreate: Above and BeyondPixelmon ModpackRLCraft

Next steps

Tune JVM settings above, then shop a dual-channel kit — or dig into stutter causes and platform guides.

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