Kioxia XG6 (OEM) 1 TB vs Samsung PM991 (OEM) 512 GB
Short answer: which is best?
Kioxia XG6 (OEM) 1 TB is 82.6 % stronger than Samsung PM991 (OEM) 512 GB. Kioxia XG6 (OEM) 1 TB ranks #33 of 54 measured system drives at WhatFPS (8,007 Drive score over 1 verified runs). Samsung PM991 (OEM) 512 GB ranks #50 of 54 measured system drives at WhatFPS (4,385 Drive score over 1 verified runs). The numbers are measured in 2 verified WhatFPS runs — not estimated, not self-reported.
Measured comparison
| Metric | Kioxia XG6 (OEM) 1 TB | Samsung PM991 (OEM) 512 GB |
|---|---|---|
| Drive score (the drive's own performance: sequential read + 4K IOPS) | 8,007 | 4,385 |
| Best rig (GAMING — whole PC) | 3,675 | 4,283 |
| Sequential read | 2,130 MB/s | 1,237 MB/s |
| 4K IOPS | 10,564 | 5,455 |
| 4K latency, median (lower is better) | 89 µs | 176 µs |
| Type | NVMe SSD | SATA SSD |
| Size | 1 TB | 512 GB |
What the numbers mean
The drive score is the system drive's measured performance in the rigs it sat in — sequential read and 4K IOPS, unbuffered. PCIe generation, fill level and driver affect it. GAMING is the whole rig's score. We show both and never mix them.
All numbers come from our benchmark suite, the same test on every PC, written in Rust with no middleware. The methodology is open at https://whatfps.com/metodik
All measurements for Kioxia XG6 (OEM) 1 TB · All measurements for Samsung PM991 (OEM) 512 GB