Well after it appeared that the Dust-off blowout had possibly cured the issue, I began to have an increasing frequency of freezes and then something took a dump recently, the system no longer boots. Will take the opportunity to de-clutter and de-fan as much as possible. Originally had switched the Galax LP 750Ti for EVGA 750Ti ITX due to increased room at the front of the S4 for the early HD-Plex 160W which has a short ATX extension to plug into the mobo. Picture below is the current state of affairs.
I only really needed the 750Ti for HDMI > 1080 resolution for my monitor as the 3770K mobo is showing its age. I don't game so for the update snared an MSI 1030 OC passive off of the bay for cheaps, a downgrade performance-wise for sure but completely adequate for the purpose. The SSDs will go to an external enclosure for backup/mass-storage usage. Will try to use the 19-pin USB mobo header for M.2 SSD drive replacement and a newer direct plug HD-PLex 160W to replace the older one, these headers seem to go unused much of the time on SFF build might as well put it to good use.
The 19-pin to dual USB3.0 card is actually too tall to fit but it will be used to check the viability. For a tentative replacement have a few things coming, only need about a 1/4" and can dump the SATA clutter.
Will try a full compressor blowout and re-seat RAM etc before re-assembling hopefully all it takes to get back up and running.
Edit: Post mortem (no pun intended) won't even get to BIOS screen anymore plus some weird power up behavior, pwr led and fans come on briefly the go off briefly then come on, neither mobo or original gpu outputs show any activityafter all plus swapping in new ram i had. Neither cpu nor mobo worth throwing cash at. Maybe look for a cheap mobo/cpu/ddr4 ram combo.
Edit2: Always use Timeshift for backup. I was in the middle of updating the Nvidia drivers from the PPA when the last freeze occurred. Looks like it bonked my kernel. Was able to eventually boot just using the mobo DP output but in rendering mode. Burned another SSD with latest LM19 going thru the normal Nvidia driver BS now but looks OK.