Converted laptop build user : Just do it. Make that move to newer hardware.

[Sirius1]

Unexpectedly I ended up with a new hardware build after fighting a WAN connectivity issue with my laptop OPNsense setup:
https://forum.opnsense.org/index.php?topic=12864.msg59623#msg59623

As other historical posts suggested, these 'hotplug' errors and WAN cycling events did end up being a physical issue, but not at all as expected: rather than USB or the USB-Ethernet adapter, it was faulty Ethernet/failing ports on my apparently dying Arris TG862G gateway.

In the process, I learned that running an older laptop as a cost saving option may not be as efficient as originally thought. In addition to the potential stability issues of running Ethernet via USB, the performance and power efficiency just can't compete with newer hardware, even against low-cost desktop PC hardware.

Old build: 19.1.8
HP ProBook 4245s AMD Athlon II P340 (25W TDP), 6GB RAM, and Plugable USB2.0 Gigabit adapter as outside WAN. Onboard Realtek as 'LAN' interface (with 8 internal VLANs).
Without any dedicated metering, and depending on the LCD display and adding and subtracting load on my TrippLite UPS, I determined the idle load to be around 28W, with peaks up to 35W. And it ran HOT. Always near 70C or above.

New build: 19.1.9
* First I fixed the gateway issue with a Netgear CM500V modem (need voice support).

* Next a Dell Optiplex 3020 off-lease refurbished from Dell Financial. https://www.dellrefurbished.com/ For just over $100 USD, this included an i3-4160 CPU and 4GB of DDR3L RAM. Replaced the included 250GB HDD with an OCZ Vertex4 128GB SSD from the parts drawer.

* From Ebay: HP NC360T dual-port Gigabit Intel-chipset PCIe (same 8 VLANs on inside): $16 USD. Lower power LGA1150 Pentium G3250T CPU: $17 USD.

All in, I was under $150 USD for the Dell, dual Gig-ethernet, and low-TDP CPU, and already have a future upgrade path by going back to the original i3-4160.

Key lessons learned:
Off-lease just can't be beat IMO. I usually build or upgrade my own, but I've had very good luck with Dell Financial. After 5 home laptops, this was my first desktop purchase. Stock can change rapidly and they have promotions frequently, so decide what you want and watch for the best builds and deals. The off-lease are business models, and typically just past their initial 3-year warranty coverage.

* Look for SFF 'small form factor' models: They are, typically, the smallest enclosures with PCIe slots (half-height). The smaller USFF (Ultra-small) and micro-Desktops don't have expansion slots for ethernet cards. I'm not a fan of WAN as a VLAN on a single Ethernet interface, or trying to kludge together a solution with a micro expansion slot for another interface.

* Alternate lower-TDP CPUs: Pay close attention to the CPU benchmark ratings, both within the low-TDP models, and comparing to your existing CPU. With the LGA1150 models I was looking at in the Pentium G class, there was a fairly substantial cost differential, but insignificant performance difference IMO. I ended up going with the lowest-cost option to reduce the payback time, maybe as low as 1 year. Low TDP, but more powerful Core-class i3 CPUs just weren't worth the cost for me, at 2-3 years recovery minimum, or significantly more. Figure out the cost/benefit for your scenario and even if swapping a lower power CPU is worth it.

Yes I did look, but also didn't really consider any of the micro cases or SoC-type models from Zotac, PCEngines, QOTOM, etc, for both cost and CPU performance reasons. I really didn't want performance in the range of the AMD P340 I was moving from, and at $1 per watt, per year, the payback for anything substantially more power efficent, like nearer current-gen low-TDP Core mobile CPUs, just isn't there until years out.

Power results:
Again using the LCD on the TrippLite, the Opti3020 with the original i3-4160 (54W TDP) appeared to idle at 28W, and peaked out around 50W, with CPU temps in the low 40C range. PowerD was set to Minimum.

* I switched to the G3250T (35W TDP) and also see idle around 28W, with minimal increase under load (no change within the minimum sensitivity delta of the UPS metering, apparently +/- approx 7 watts). Temps running in the mid-30C range. Now the i3 was running 0-10% most of the time, and the Pentium is running 10-20%, but will likely not see any performace hit with my 150/10 Comcast cable connection and 4 home users. Both are far more powerful than the AMD I ran previously. Turning on IDS/Suricata on WAN, the G3250T is in the 20% range, and running ~40C. PowerD is set to Adaptive.

The verdict:
For now I plan to run the Pentium, and will swap the i3 back in if need a performance boost, or AES.
As widely reported, the 4th gen Haswell desktop CPUs seem to run very efficently, and mine is using the same (or less) power than the older laptop CPU under idle. The more efficient G3250T, even though a desktop CPU, appears to be matching the power efficiency of the old AMD mobile CPU under both idle and load....with more than 2x the CPU performance rating, and at nearly half the temp.

So in the end I may not even have needed to replace my build. But it took the same WAN failures with the newly configured Opti3020 and Intel NICs to realize the issue was the gateway, and not USB Ethernet. Now I have a new and higher performance build with zero WAN errors, and none expected with the Intel-based NICs. I even ended up matching the power efficiency of the old HP laptop I had in place with substantially better performance. Win, win.

If this scenario sounds familiar, hopefully this gives a few more options and some data bits to think about as you consider new or replacement builds.

[chemlud]

Are you crazy? All optis will be sold out the next time I need one! ;-)

Comparable setups here. Dell rulz... Hope the BIOS get further updates and these are not messed up by... who knows...

[oneplane]

For anyone stumbling upon this topic; they don't ship outside the US, Canada or UK, so unless you can do shipment there it's sadly not an option.