ATM10 Server Setup: RAM, Java 21 & Performance

All the Mods 10 is one of the largest kitchen-sink modpacks available for Minecraft right now. With over 400 mods running on NeoForge for Minecraft 1.21.1, it packs in tech, magic, exploration, and automation systems from nearly every major mod developer. It’s also one of the more demanding packs to host, and the default settings most people start with aren’t going to cut it.

ATM10 needs the right Java version, enough RAM, and a few server tweaks if you want it to run smoothly.

What You Need Before Starting

ATM10 has three hard requirements that differ from most modpacks. Miss any of them and your server won’t start.

Java 21 - ATM10 runs on NeoForge for Minecraft 1.21.1, which requires Java 21. Java 17 won’t work. Java 8 definitely won’t work. This applies to the server and to every player connecting. If you’re hosting with WinterNode, you can set the Java version from the Game Control Panel under Configuration > Server Options. Our Java version selection guide walks through the process.

NeoForge - ATM10 uses NeoForge, not Forge. They’re closely related (NeoForge is a fork of Forge that emerged around 1.20.1), but they’re not interchangeable. If you’re installing through the Modpack Manager, this is handled for you. If you’re doing anything manual, make sure you’re installing NeoForge and not legacy Forge.

10GB+ RAM - This is a 400+ mod pack. It won’t load into memory on 4 or 6GB no matter how patient you are. 10GB is the floor. More on this below.

RAM Recommendations

RAM allocation for ATM10 is a balancing act. Too little and the server can’t load the pack. Too much and Java’s garbage collector spends more time cleaning up unused memory than running the game, which shows up as periodic lag spikes and stuttering.

Here’s what we recommend based on player count and what we see running on our hardware:

A few things to keep in mind:

Don’t over-allocate. Throwing 20GB at an ATM10 server when 12GB would do isn’t free performance. Java’s garbage collector has to sweep through all that allocated memory periodically, and larger heaps mean longer GC pauses. If you’re seeing periodic freezes lasting 1-3 seconds, you might actually have too much RAM allocated rather than too little.

RAM usage climbs over time. A fresh world on day one uses less memory than the same world after two weeks of exploration, base building, and automation. The machines your players build - especially ones involving item transport, mob farms, and chunk loaders - push memory usage up steadily. Plan for where your server will be in a few weeks, not just where it starts.

Client-side RAM matters too. Your players need 8-10GB allocated in their launcher settings. ATM10 is just as demanding on the client as on the server.

Installing ATM10 via the Modpack Manager

If you’re on WinterNode’s Minecraft hosting, the Modpack Manager is the fastest path. It pulls directly from CurseForge and handles the NeoForge installation for you.

Step 1: Set Java 21 first. Before installing anything, go to Configuration > Server Options and set the Java version to Java 21. Do this before the pack install so NeoForge launches correctly on the first boot.

Step 2: Open the Modpack Manager. Navigate to Tools > Modpack Manager in the Game Control Panel. Search for “All the Mods 10” or “ATM10.”

Step 3: Install the pack. Click Install and choose Format Server if this is a fresh server with nothing on it. If you have existing data you want to keep, back it up first - Format Server wipes everything.

Step 4: Allocate your RAM. Under Configuration > Server Options, set the memory allocation to at least 10GB. For most groups, 12GB is a better starting point.

Step 5: Start the server and wait. The first boot is slow. ATM10 needs to load 400+ mods, generate configs, and set up the initial world. Expect this to take 3-8 minutes depending on the pack version. Don’t panic if the console is quiet for a while - it’s working. Watch for “Done” in the console output before trying to connect.

For more details on the Modpack Manager workflow, our modpack installation guide covers the full process including troubleshooting common issues.

Performance Settings

ATM10 is playable out of the box, but the default server.properties settings are tuned for vanilla Minecraft. With 400+ mods generating custom terrain, structures, and entities, you’ll want to tighten things up.

View Distance and Simulation Distance

These are the two biggest levers you have.

Open server.properties in the File Manager and adjust:

view-distance=8
simulation-distance=6

The default view distance is 10 and simulation distance is also 10. Dropping view distance to 8 means the server sends fewer chunks to each player. Dropping simulation distance to 6 means entities, redstone, and mob AI only run within 6 chunks of each player. Both reduce the per-player CPU and memory load significantly.

If you’re running 10+ players, you can go as low as view-distance=6 and simulation-distance=4, though players will notice the shorter draw distance. It’s a tradeoff between visuals and stability.

Pre-generate Your World

New chunk generation is the single biggest performance hit on any Minecraft server, and it’s worse on modded because every mod that adds worldgen features (ores, structures, biomes, dimensions) multiplies the work per chunk.

Pre-generating a radius of chunks around spawn before your players join eliminates this entirely for explored areas. The Chunky mod (included in ATM10) or the Chunky plugin can handle this. Our pregeneration guide covers the full process, including how much to generate and how long it takes.

Entity Management

Modpacks like ATM10 add dozens of new mob types, and the cumulative entity count climbs fast. If your TPS starts dropping, check your entity counts first. A few things help:

• Mob farms need limits. If players are building mob grinders, the entity count from accumulated mobs can tank the server. Encourage kill mechanisms rather than storage-based designs.
• Item entities on the ground. Automated systems that drop items on the ground instead of piping them into inventories create entity pressure. This is a common issue with early-game automation before players have proper item transport set up.
• Limit animals in pens. Breeding 200 cows in a single chunk is a classic TPS killer. Most players don’t realize how much server time animal AI eats.

For a deeper dive on server-side performance tuning, our server optimization guide covers the full range of settings across spigot.yml and paper-world-defaults.yml - though note that ATM10 runs on NeoForge, not Paper, so some of those config files won’t apply. Focus on server.properties and any mod-specific performance configs.

Troubleshooting Common Issues

Wrong Java Version

Symptom: Server fails to start. Console shows UnsupportedClassVersionError or references class file major version 65.

Fix: Set Java to 21 in Configuration > Server Options. This is the most common ATM10 issue we see in tickets. Our Java version guide has the full version table.

Out-of-Memory Crashes

Symptom: Server crashes with java.lang.OutOfMemoryError: Java heap space or just stops responding.

Fix: Increase your RAM allocation. If you’re at 10GB, move to 12GB. If you’re already at 12-14GB and still crashing, the problem might be a specific mod or automation build creating a memory leak rather than a raw allocation issue. Check the crash log for which mod is referenced in the stack trace.

First Boot Takes Forever

Symptom: Server has been “starting” for 15+ minutes and the console seems stuck.

Fix: ATM10’s first boot is genuinely slow - 3-8 minutes is normal. If it’s been more than 15 minutes, check the console for error messages. A common culprit is insufficient RAM causing the server to thrash during mod loading. If you see repeated GC overhead warnings, increase your allocation.

Players Can’t Connect

Symptom: Players get “Incompatible mod set” or a disconnect with a list of missing mods.

Fix: The player’s ATM10 version doesn’t match the server. Both sides need the exact same pack version. If you updated the server, your players need to update their client too. Make sure they’re installing ATM10 through CurseForge, Prism Launcher, or ATLauncher - not trying to piece it together manually.

What to Tell Your Players

Before anyone tries to connect, share this checklist:

1. Install Java 21 on their machine. Most launchers handle this automatically, but if anyone is on an older Java install it won’t work.
2. Install ATM10 through a launcher - CurseForge app, Prism Launcher, or ATLauncher. Don’t download mods individually.
3. Allocate 8-10GB of client RAM in their launcher’s JVM settings. The default 2-4GB that most launchers start with is nowhere near enough. Going over 12GB on the client is unnecessary and can cause the same GC pause issues as the server.
4. Match the pack version exactly. If the server is on one version of ATM10, every client needs to be on that exact same version. The version is shown on the CurseForge page and in the launcher.
5. Expect a long first load. The client takes 3-5 minutes to load ATM10 for the first time. Subsequent launches are faster.

Run ATM10 Without the Headaches

ATM10 is a big pack with big requirements, but it doesn’t need to be complicated. Set Java 21, allocate enough RAM, tune your view distance, and pre-generate your world. That gets you 90% of the way to a stable server.

WinterNode’s Minecraft hosting starts at $1.99/GB with no CPU limits, which means your server can burst when it needs to during heavy mod loading or chunk generation. No throttling, no surprise performance caps. A 12GB ATM10 server runs $23.88/month.

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