https://us.community.samsung.com/t5/Monitors-and-Memory/Samsung-990-PRO-2TB-Performance-Degradation-After-7B2QJXD7/m-p/3391894#M17449 <P>In investigating further, I noticed that SMART data for the 2TB and 4TB 990 Pro SSDs report the same number of power cycles (the drives were both installed at the initial build in February) but much different power-on hours. Similar results were also apparent from earlier tests in September using the older firmware.</P><P><STRONG>8 Sept 2025; 4B2QJXD7 firmware</STRONG></P><P><STRONG>metric // nvme0 (4TB) // nvme1 (2TB) // ratio/delta</STRONG></P><P><STRONG>Power Cycles //</STRONG> 689 // 689 // 1.0x</P><P><STRONG>Power On Hours // 945 // 2,108 // 2.23x</STRONG></P><P>Temperature // 33°C // 39°C // +6°C</P><P>Controller Busy Time // 978 // 1,899 // 1.94x</P><P>&nbsp;</P><P><STRONG>23 October 2025; 7B2QJXD7 firmware</STRONG></P><P><STRONG>metric // nvme1n1 (4TB) // nvme0n1 (2TB) // ratio/delta</STRONG></P><P><STRONG>Power Cycles // 821 //</STRONG> 821 // 1.0x</P><P><STRONG>Power On Hours // 1,025 // 2,447 // 2.39x</STRONG></P><P>Temperature // 31°C // 45°C // +14°C</P><P>Controller Busy Time // 1,118 // 2,224 // 1.99x</P><P>&nbsp;</P><P>The odd counting of power_on_hours is either intentional or it's a bug spanning at least 2 firmware versions.&nbsp; Weird, eh?</P><P>Regardless, the firmware update seems to have caused thermal issues.</P><P>Temperature comparison (both drives in same system):<BR />- 8 Sept (4B2QJXD7): 2TB=39°C, 4TB=33°C (6°C difference)<BR />- 23 Oct (7B2QJXD7): 2TB=45°C, 4TB=31°C (14°C difference)</P><P>The 2TB drive's temperature increased by 6°C after the firmware update, and the temperature delta between drives more than doubled.</P><P>This thermal increase, combined with the 70% performance loss, suggests that the 7B2QJXD7 firmware is causing the 2TB drive to work much harder internally, possibly due to excessive write amplification or garbage collection activity.</P> Fri, 24 Oct 2025 20:25:19 GMT SFdrifter 2025-10-24T20:25:19Z