I'm upgrading my prebuilt PC and bought a WD Black SN850X to use alongside my existing ADATA Legend 860. I was thinking of keeping Windows and less demanding games on the ADATA drive while installing larger games and Steam downloads on the WD drive. Steam downloads and especially game updates often make the entire PC feel unusably slow: disk usage reaches 100%, downloads pause frequently, and simple tasks such as opening Chrome or the taskbar can take several seconds.nnWould putting Steam and its game files on a separate SSD from the operating system make the system more responsive while downloading? Is it realistic to maintain around 500 Mb/s during Steam downloads, or are the pauses caused by Steam unpacking and patching files? Could another component, firmware issue, or storage problem be responsible? The ADATA drive is only about 60% full and health checks report it as healthy. I'm using Ethernet rather than Wi-Fi. The rest of the system is high-end, with a Ryzen 7 9800X3D, RTX 5080, and 32 GB of DDR5 memory.
3 Answers
The SN850X should have much better sustained write performance than the ADATA drive, particularly during large writes. Some QLC SSDs can write quickly while their cache is available, then slow down dramatically once that cache is exhausted. Keeping an SSD below roughly 80% full helps, and yours being around 60% full is reasonable. Still, a normal 500 Mb/s internet connection is only about 62 MB/s, so even a slower SSD should usually handle the network speed during a straightforward download. The slowdowns are more likely to appear while Steam is unpacking or rewriting a large existing game.
Check the SSD firmware, motherboard BIOS, chipset drivers, and drive temperatures. Also look at Task Manager while the problem occurs: if the CPU is busy, Steam is probably decompressing or patching; if the drive is busy with low transfer speeds and high response time, storage activity is the limiting factor. Running a memory test and a full storage-health check would also be sensible. Ethernet rules out many Wi-Fi problems, but you can still check for network errors separately. With a 9800X3D, ordinary Steam downloads should generally be fine, but unusually slow game updates can simply be caused by inefficient patching rather than a faulty component.
A separate drive may help keep Windows responsive, especially if Steam is constantly reading and rewriting game files on the same drive as the OS. You can put Steam and demanding games on the SN850X while leaving Windows on the ADATA drive. However, the SSD itself may not be the only cause. Steam downloads compressed data, then unpacks and patches it immediately, so CPU usage and the way a particular game stores its files can become the bottleneck. Large updates for games such as ARK can take much longer to patch than to download, even on fast hardware.
That seems to match what I’m seeing. A 37 GB ARK update was estimated to take around 14 hours because the drive briefly reached about 200 MB/s, then dropped to roughly 10 MB/s for several minutes at a time. Reinstalling the whole game can actually be faster than patching it.