PC Does Not Start With Four RAM Modules at 4000MHz
PC Does Not Start With Four RAM Modules at 4000MHz
I recently upgraded my gaming PC by adding two more RAM sticks, raising the total memory to 32GB. After installing and configuring XMP at 4000MHz, the system started failing to boot, showing diagnostic errors before eventually crashing. My motherboard specs include an i5 7640X with a 4-thread HEDT, Asus Tuf X299 Mark 2, a 4000MHz Patriot Viper Elite 2 PSU, an AMD Vega 56 M.2, a Samsung 2TB HDD, and a Western Digital 80GB HDD. Initially, the new RAM caused issues at full speed, but booting with only the new sticks worked. When testing with older RAM, everything functioned normally. Now, when all four sticks run at 4000MHz, the PC refuses to start. Could you help explain why this happens and suggest a solution?
Memory controllers prefer slower RAM paired with storage. In short, for speed go dual sticks. For more space choose four sticks. You can't really have both high speed and large capacity at the same time. A 2x16 kit gives you about 32 GB, or if you want serious storage you can splurge on a 2x32 GB 3200 MHz DDR4 system for 64 GB. Beyond that it's tough to get good performance. Your 7640 with 4000 MHz RAM is impressive, but unless you're joking, you might be one of the rare buyers who got that old CPU.
Four sticks provide dual rank performance, but dual rank memory is significantly more challenging to manage at high frequencies compared to single rank memory. On my 7700K (though the CPU is different, this is what I’ve experienced directly, and memory controllers should be sufficiently aligned for this comparison), it achieves 3866MT/s with single rank while only reaching 3200MT/s with dual rank. If it stalls at 3600, stick with that frequency—likely the CPU’s ceiling. You might experiment with VCCSA and VCCIO voltages to see potential improvements, but expect no substantial boost beyond what’s already there.
It's an extremely powerful processor, easily surpassing my FX 9590. Running all eight RAM slots with a compatible CPU would likely limit memory performance. Upgrading to faster RAM wouldn't necessarily solve the issue if the CPU can't keep up.
Generally on all consumer and prosumer HEDT systems, more RAM reduces performance. 8 dimms would likely stop before reaching 3000-3200, let alone 4000. The problem isn't the RAM speed itself, but the CPU's memory controller. That's why high-capacity kits often lag because they aren't optimized for those speeds. Unless you're comfortable with uncertain products that probably won't work.
It wasn't possible to complete the task. The setup has limitations due to memory channel constraints, and while it might function with proper channels, performance could be affected. The X299 controller tends to lag behind the Kaby Lake X version.