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If your SK hynix Platinum P41 2TB once wrote at roughly 5,500–6,500 MB/s but now records about 1,500–3,000 MB/s, do not assume that result is normal. Multiple owners have reported the same pattern, often with read performance largely intact, but no official SK hynix statement found here proves a universal defect or a single cause. Verify the benchmark, firmware, PCIe link, temperature, free space and software state first. Back up important data before any destructive operation; if the slowdown persists under controlled testing, warranty service or replacement is more sensible than repeatedly formatting the drive.
What the P41 2TB should deliver
The Platinum P41 is a PCIe 4.0 NVMe TLC SSD marketed in the approximately 7,000 MB/s sequential-performance class. That figure is a vendor maximum under specified test conditions, not a guarantee that every computer or workload will produce 7,000 MB/s writes. The exact rated write speed depends on the current product sheet, so record the drive’s full model number and firmware revision rather than relying only on the retail name.
- Sequential read and write: large, contiguous transfers; these are the figures most product pages advertise.
- Random performance: small, scattered transfers, which matter more to many operating-system tasks.
- Burst versus sustained writes: a pseudo-SLC cache can deliver very high short-term writes before speed falls as the cache fills and data is written to TLC NAND.
- Units: MB/s and MiB/s are different, so compare results made with the same application and settings.
A short benchmark can mostly measure cache. A long test or real file copy may expose slower sustained TLC performance. A temporary drop after a very large transfer is therefore different from a repeatable low result after the drive has been idle.
What owners have reported
In the AnandTech discussion, owners described initial sequential-write results near 5,500–6,500 MB/s later falling to roughly 1,500–3,000 MB/s, with reads often remaining close to normal. Reports involve Windows 11 systems, operating-system drives, secure erases, fresh installations, more than one P41, and replacement discussions. These are user observations, not a prevalence study or an SK hynix defect admission. See the discussion at AnandTech and additional reports at Level1Techs.
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- INTERFACE: SATA III connection delivering reliable data transfer with read speeds up to 560MB/s and write speeds up to 510MB/s.
- PERFORMANCE: TLC (Triple-Level Cell) NAND flash memory technology ensures consistent and dependable performance for everyday computing tasks.
- COMPATIBILITY: Internal SSD designed for seamless integration with systems supporting 2.5-inch SATA storage devices.
Confirm that the slowdown is real
Prepare a controlled test
- Back up irreplaceable files before testing.
- Stop downloads, cloud synchronization, antivirus scans, virtual machines and other storage-heavy work.
- Let the computer and drive idle for several minutes.
- Keep substantial free space; 10–20% free is a practical starting point, not a manufacturer rule.
- Record the model, firmware, host writes, temperature, motherboard slot, PCIe generation and lane width, and whether the P41 is the boot disk.
Repeat comparable benchmarks
Use the same CrystalDiskMark version, profile and test size used for earlier results. Run it two or three times after idle, then compare with a run immediately after a large write. Record sequential and random-write results. Do not compare screenshots made with different queue depths, test sizes or data patterns as though they were equivalent. CPU, motherboard routing, thermals, encryption, power management and background activity can all change the number.
Check non-destructive causes first
Firmware
Open the current SK hynix support portal at ssd.skhynix.com. Confirm that the utility recognizes the exact capacity and model, note the installed firmware, and check whether an applicable update is offered. Follow its backup, reboot and data-loss warnings. Community posts mention firmware 51061A20 and possible improvement after updating, but no authoritative release note here confirms that version or what it fixes. Treat those claims as leads, not proof.
PCIe generation, lanes and slot
Use a hardware-information utility or motherboard firmware to verify PCIe Gen4 x4 where supported. Gen3, x2 or x1 operation can substantially reduce throughput. Test the primary M.2 slot, especially on desktop systems with multiple NVMe drives or expansion cards sharing CPU or chipset lanes. Temporarily stop activity on other storage devices and retest. Laptops and chipset-connected slots may have platform limits that cannot be fixed in software.
Temperature and cooling
Watch temperature during a sustained benchmark. A speed decline that tracks rising temperature and recovers after cooling is consistent with thermal throttling. A heatsink does not eliminate every thermal problem, and one heatsink-equipped owner still reported the P41 symptom, so temperature is a check rather than a complete explanation.
Operating-system and workload conditions
The original report compared Windows 11 21H1 and 22H2, but that is correlation, not proof that Windows caused the change. Install current Windows updates, motherboard BIOS and chipset drivers. Note whether BitLocker or other encryption is active, which power plan is selected, whether PCIe Link State Power Management is aggressive, and whether the P41 is the system volume. If possible, test it as a secondary drive or from a clean operating-system environment. One participant said enabling Windows Large System Cache restored sequential results but not random-write performance; that is an anecdotal workaround, not a general recommendation.
TRIM, cache behavior and safe recovery steps
Run TRIM without deleting files
In an elevated PowerShell window, run:
Optimize-Volume -DriveLetter C -ReTrim -VerboseReplace C with the correct volume letter. ReTrim informs the SSD which blocks are no longer needed; it is not a secure erase. Reboot, let the drive idle, and repeat the controlled benchmark.
Understand the cache distinction
A drive can be only half full yet still have its cache affected by recent writes, garbage collection and test size. Conversely, a long transfer that slows only after cache exhaustion may be normal sustained-write behavior. A low result that remains after idle, appears in repeatable standardized tests and returns after apparent recovery is more concerning than a one-time post-cache dip.
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Secure erase or clean installation
Secure erase destroys accessible data and should be considered only after a verified backup and a safe, supported NVMe erase or sanitize procedure. Reports conflict: one owner saw no improvement after secure-erasing and restoring an image, while another reported recovery after secure erase followed by a fresh Windows 10 22H2 installation. A full image can restore the same software state, so a clean-install comparison is more informative. Do not use an untrusted third-party erase tool simply because the vendor utility lacks the feature. Repeated formatting is not routine SSD maintenance.
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| Observed pattern | More likely explanation | Next action |
|---|---|---|
| High at first, then slower only during a very large continuous write; recovers after idle | Cache exhaustion or normal sustained TLC behavior | Repeat with a larger test and compare after idle |
| Drive reports Gen3, x2 or x1; results change after moving slots | Platform topology or lane limitation | Use the correct x4-capable slot and reduce competing storage activity |
| Speed falls as temperature rises and improves when cool | Thermal throttling | Improve airflow or add a compatible M.2 heatsink |
| Formerly normal drive now repeatedly writes at about half speed while reads remain normal | Possible firmware, cache-management or drive-specific degradation | Verify firmware and software state, back up, then consider warranty service |
| Slowdown accompanied by timeouts, disappearing volume, freezes or abnormal SMART values | Possible drive failure | Stop benchmarking and clone or back up immediately |
When warranty service is the practical fix
Escalate when controlled tests still show approximately half-speed writes after firmware, link, temperature, free-space and software checks; when performance repeatedly collapses after recovering; or when errors, hangs or abnormal SMART indicators appear. A healthy SMART percentage does not rule out a controller, firmware or performance problem.
Prepare a support package containing:
- Exact model, capacity, serial number and firmware revision.
- SMART or health screenshot, including temperature, host writes and error fields.
- PCIe generation and lane width, motherboard or laptop model, and M.2 slot used.
- CrystalDiskMark version, profile, test size, data pattern and dated before/after results.
- A timeline of when performance changed and the operating-system or hardware changes around it.
- Purchase receipt and seller or region information.
Users have reported refund, RMA or replacement discussions, including a later report describing a refund offer at AnandTech. Warranty outcomes depend on country, seller, purchase date and applicable terms; no replacement or reimbursement is guaranteed.
Should you keep the P41 or replace it?
Keeping the drive is reasonable when the lower result is explained by cache exhaustion, a PCIe limitation or heat, the drive is stable, SMART shows no concerning indicators, and your workload is unaffected. A persistent unexplained decline, a recurring collapse after recovery, or any instability makes replacement or warranty service the safer choice.
If you need a replacement, compare current products and warranty terms rather than assuming any model is immune to performance issues. The WD_BLACK SN850X 2TB is specified at up to 7,300 MB/s read and 6,600 MB/s write, 1,200 TBW and a five-year limited warranty in its data sheet: official specification. The WD_BLACK SN7100 2TB is specified at up to 7,250 MB/s read, 6,900 MB/s write, 1,200 TBW and a five-year warranty: official specification. Those headline figures still require a compatible PCIe 4.0 platform.
Bottom line
A P41 2TB repeatedly writing at roughly 1,500–3,000 MB/s instead of its former 5,500–6,500 MB/s is a credible, repeatedly reported symptom, not automatically normal behavior. Establish a repeatable baseline, check firmware, link width, temperature and software conditions, run TRIM, and protect your data. Use secure erase only as a last-resort diagnostic. If the result remains low or the drive becomes unstable, document the evidence and pursue warranty service or replacement.
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