Im not looking to do anything specifically fancy just upgrade to a "silent board" for both that is plug and play where i take it out of the box and plug everything in and not have to do any splicing or change to any wires at all.  what would be the best board to go with?

I should be able to update the firmware via octoprint correct?

I used the following on my E5Plus and it was direct plug and play. A small pair of sharp needle nose tweezers helps to remove all the hot glue holding on the connectors.

https://www.microcenter.com/product/632876/creality-upgraded-ender-5-plus-silent-mainboard,-silent-motherboard-with-tmc2208-driver,-customized-super-quiet-mute-board-for-cr-10s-cr-10-s4-cr-10-s

A lot of people dont have luck with the included firmware. Probe points are off vs reality or bed location vs limit switches is wrong, or the CR Touch/ BL Touch doesn't work, etc etc.

You may need to compile your own firmware. You may not.

If there is anything I've learned, it is that there is no consistency in the Creality Universe. You can buy two E3s from the same pallet, one prints like horse shit and the other can keep up with a Prusa. Its seemingly random.

The Ender 5 and 5+ come with 4.2.2 boards which are quite noisy. If you upgrade to the 4.2.7 board (same Creality board in Ender 5Pro), it has the less noisy drivers. Whisper like even.  That's the cheapest and most "OEM" way to do it. I went with BTT SKR Mini 3 V2 boards and LCD's. While they are phenomenal, they are pricey. BTT has wiring diagrams for the board and Kersey Fabrication (U-Toob) has Marlin firmware for those boards and Ender's. The 4.2.7 and BTT boards will also allow you to run level detection with a BT Touch or CR Touch

I've done the Zero G Merc1 mod to my Ender 5. Running a BTT SKR Mini V2 board I think. Running Klipper firmware and a Rapido UHF hotend.

https://zerog.one/

I highly recommend this mod. If you print PLA it has the potential to print faster than my Bambu P1S and QIDI X Plus 3 printers. I don't have my accelerations set as high on my Merc1 as those, but I can push more plastic with the higher volumetric flow.

Get the ObXidian Nozzle for the Bambu.

I can print PLA at 40mm³/s. PETG at 35mm³/s.

This thing is WILD with it.

I was thinking this might be a good alternative. I like it has a 60W heater, but after reading some reports Bambu apparently updated the firmware to detect CHT nozzle use. I need to investigate that more.

Haldis TZ-3.0

At least the ObXidian nozzle is certified for Bambu though. I'm still doing reasearch.

i did the factory silent board.  not the most feature packed option, but certainly an easy one, as it was drop in and ready to go.  that sorted out the noise and also ridging/banding and other artifacts caused on the surface by the cheap motor drivers on the old board.

I am using the crap out of it right now, but when I slow down, I need to do some further testing.

As you know, PETG doesn't like to be printed fast typically. I have not experienced that at ALL with this Bambu.  I print it at over 30mm³/s and over 150mm/s linear speed and it simply is perfect. Perfect layer adhesion. It's unreal.

When running max flow rate calibrations, usually you'll start to see the single wall break down, start to tear away from the base as it lacks adhesion, or your hotend simply runs out of heat and the sheen (in the case of PETG at least) will change, and that's pretty much when layer adhesion goes to crap.

Well I started at 10, went to 15. Perfect.

Okay, start at 15 and go to 20. Still perfect.

F this. I need this to fail. Ran an extended test from 20-30. STILL perfect.

at 30mm/s it's running 1.5x faster than I got my MK3S to achieve, and the MK3S had a 50w Slice Engineering heater cartridge, a CHT Nozzle, and a Mosquito hotend. It doesn't get much better than that on a Prusa, and this thing is literally at LEAST 50% faster still on flow rate, and 10x faster (minimum) on acceleration. Linear speed (at my nozzle size and layer heights used, which is 0.6mm nozzles between 0.2 and 0.4mm height) is still over double, 150 vs. 75 max on the Prusa.

I need to do extended testing but I'm iterating a prototype product, and my kids want Pokemon printed.