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Minecraft ModpackJava 17

Optimal RAM for RLCraft

Allocate about 6GB JVM heap for RLCraft, on a 16GB+ dual-channel system so Windows is not starved. Prefer Java 17 with Generational ZGC (Java 21); never give Minecraft more than half of physical RAM.

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JVM baseline

6 GB

System RAM target

16 GB+

Mod count

125 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 RLCraft — 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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125 Mods
Vanilla (0)Small (50)Medium (150)Heavy (300)Extreme (450+)
12 Chunks
Short (4)Normal (12)Far (18)Extreme (32)

Memory Allocation Map

8GB JVM
8GB OS
allocated to JVM Free for Windows
Recommended allocation8 GB
Garbage CollectorG1GC
JVM Stutter / Pause Risk
MODERATE (GC SPIKE)

Large G1GC heaps can hitch FPS for 100ms+ — prefer Java 21 + ZGC at 6GB+.

Minecraft Modpack presetJava 17 runtime

Optimized JVM arguments console

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

-Xms8G -Xmx8G -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)

What is the standard RAM allocation for RLCraft?▼
We recommend allocating exactly 6GB of RAM. RLCraft runs on an older Minecraft version (1.12.2) which is highly CPU-bound, making 6GB the perfect balance between asset caching and garbage collection speed.
Why does RLCraft stutter when I generate new chunks?▼
New chunk generation in RLCraft spawns complex structural designs and dense foliage. This creates a massive surge in garbage objects, causing lag spikes if you are using unoptimized JVM arguments.

Related Minecraft profiles

Better MinecraftCreate: Above and BeyondPixelmon ModpackStoneBlock 3Vault Hunters 3

Next steps

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

Open RAM Finder (16GB+)Best live dealsModded Minecraft stutter guideAll game RAM guidesCompatibility hub