Let's knock this out as nice and easy as I can.
Always remove steel bases and trays. This is a steel tray that a card or board is screwed or riveted into. If it's rivets I'd suggest an invaluable tool. Tekton and Dewalt both have low profile nail snips. Cost is less than $10. And not have been able to snip through ANY rivet I've had to. Leaving a plate on the board automatically makes the best gold cap board peripheral and most other will drop to midgrade. So figure it out and get that tray off!
The standard external mounting bracket can stay on if you want.
Remove any heatsinks larger than a quarter of the board size and or large across than a silver dollar. Leaving these on will downgrade you one class.
Remove ALL steel heatsinks. If it sticks to a magnet remove it.
Remove all batteries, be they round button cell batteries, canister batteries (think fat AA and C batteries), or mounted pin batteries like the Dallas clock batteries.
Never remove soldered IC chips. Be they ram or controllers or CPUs, if it's soldered on leave the ICs alone.
Removing one and you may get away with it. Remove two and you drop a grade (or two). Any more than that and the best you'll get is peripheral. It's almost never worth it. Exceptions? You may consider removing gold cap CPUs from a gold cap chip board with many many gold chips if the CPUs use half pins in a pin through design. These will fall into the lowest gold cap cpu rate of iBM/VIA gold caps.
Don't remove bga gold caps; in general the best you will get is pentium/Mac ceramic. And most can fall into pinless or IC. Sad but true.
Never remove fingers from ram. I've yet to find a single ram stick worth more as a pair of fingerless ram and gold fingers, over the straight ram price.
There are three styles of slot processors. Always remove the cover and heatsinks if included on yours. Most are screwed or glued on but some use rivets you have to cut through.
The two rectangular ones should never have their fingers cut off. The pair of trimmed slot processor and fingers are always less valuable than the whole processor.
The highest end AMD and Xeon processors of the third design, looking like a flat pyramid, can still survive the telco rate without their fingers. These are few and far between though and the majority of pyramid slot processors missing their fingers get trimmed slot processor rate. That exceptional design has the processor, three green fibre co processors, a controller on the back side and hundreds of ceramic monolithic capacitors.
Gold finger cards? I've found about 75% of gold finger cards are worth more as a gold finger card than as gold fingers and a trimmed finger card. That roughly 25% that are worth more with their fingers off are because the board still clears telco. These are usually memory expansion cards, workstation graphics cards, and later generations gold finger game cartridges. I.e. N64, and game boy advance.
Brown boards. Let me be clear here. A commercial brown board will never be Better than peripheral rate. Most are low grade. Here's the list of exceptions you should post photos for
Floppy drive boards. With a gold finger or gold pins. Usually peripheral.
Remote control boards. Usually midgrade and occasionally peripheral.
PRE 80s audio and video unit boards. Such as early vcr and Betamax players. Amplifiers. Projection units. These all have brown boards that may get midgrade or even peripheral. Due to the large amounts of silver solder and gold pin connections.
Non commercial, meaning hand made, brown boards can sometimes go even higher. But these are very very rare boards. Examples come from electric organs, medical equipment, phone switches, and wiring boards which and on occasion get a quoted pin board rate or even telco. These have nickel silver and gold pins, excessive amounts of silver nickel solder. Few or no low value metals, lots of ceramic silver resistors vs ceramic copper resistors and silver capacitors and silver vacuum tube bases rather than aluminium canister capacitors
Finally with one exception so rare we won't discuss it inline you can not UPGRADE a board by removing something not a base/tray or a heatsink. Period.
-- my grades are my own and do not represent an offer from boardsort, nor are they guaranteed. Please keep that in mind.