Hard freezes, mitigated to soft freeze with storage controller timeout/error-out.

Microsoft Windows 10 Professional (x64) Build 18362.418 (1903/May 2019 Update)

Dell T7500, barebones config save for second CPU riser, A18 bios

Cpu's are Dual Xeon X5550, stock frequency and voltage

72GB DDR3 Buffered ECC. 6x 8GB DIMM's, 6x 4GB DIMM's. All de-rated to the motherboard's 1333mhz @ 9-9-9-24 CAS latency.

GTX 1060 6GB, EVGA SSC. Out-of-box config.

Currently only on one drive, a PNY CS1311 240GB SSD assigned to the integrated LSI 1068e SAS controller.

So this is my daily driver, I've been pushing it for 6 or so years. It's run into problems since then that I've just attributed to gremlins, which have been appeased with a fresh OS install or swapping some hardware around.

In the past few months I had a minor issue, which I attributed to my USB DAC (FiiO Q1 AMP/DAC) where every few hours videos would buffer endlessly and games would stutter or act bizarrely until I unplugged and plugged in the DAC again. Could be a bad cable, or my DAC going out, wasn't a big enough issue to care.

But yesterday it started hard-freezing, as in the mouse would stop responding, everything would stop moving, in a couple instances even holding the power button down for a full minute wouldn't shut it off. No blue-screen, no errors logged, just a hard freeze. This was partially remedied when I removed every drive but the SSD I use to boot. This gave me the leeway to do hardware diagnostics on everything else. Prime95 stress testing, full memory test.

Since then and for the last dozen hours I've been getting 'softer' stalling/freezing. No applications time-out and all of them act responsive, but load endlessly. Notably this is when I started getting real info in Event Viewer (occurs in time with freezes):

Reset to device, \Device\RaidPort0, was issued.
The driver detected a controller error on \Device\RaidPort0.
The IO operation at logical block address 0x5fd598 for Disk 0 (PDO name: \Device\00000038) was retried.

Additionally when I wasn't using the computer I got a massive pile of:

The application \Device\HarddiskVolume1\Windows\System32\svchost.exe with process id 15660 stopped the removal or ejection for the device PCI\VEN_8086&DEV_3A40&SUBSYS_026D1028&REV_00\3&172e68dd&0&E0. (This is the Intel Serial ATA controller)

So my best guesses are chipset overheating/failing, or my SSD is failing. Although my chipset failing without any other symptoms would be odd because it's limited to the SAS controller, and the SSD failing wouldn't explain the constant "stopped the removal or ejection errors' seeing as it's on a SAS controller and not the Intel ATA controller that's failing to 'eject'.

*edited some formatting