Q: iMac G3 Rev A Faulty Ram?

What about trying it in the other slot?

I am no expert on that model Mac or RAM but...

1) When I do a web search using the code written on the chip I find hits referring to Samsung and other PC laptops, no Macs. Macs can be fussy about RAM and what works in a Windows box may fail on a Mac.

2) From: http://www.everymac.com/systems/apple/imac/specs/imac_ab.html

"Uses 144-pin PC66 SO-DIMM memory modules."

I wonder if yours is the wrong specifications since it says "PC133"?

Just for reference, OWC says this one is compatible but is is 100 : https://eshop.macsales.com/item/OWC/100SO256168L/

I don't know if there were any firmware updates for your computer. Sometimes adding RAM beyond original specs. requires a firmware update.

Those older Macs didn't support high density memory chips.  By the time that PC-133 memory was introduced, denser memory chips were also being introduced to expand the amount of installed memory that was supported in new Macs and PCs.  Some PC-133 had low density memory chips and some had the higher density chips, which made upgrading older computers somewhat problematic.  One had to know exactly what kind of chips were on the card, to know if it would be supported.  Does that SO-DIMM only have the 4 large chips that are visible, with none on the back of the card?  If so, you probably need a 256 MB SO-DIMM with lower density chips, which means that it will have 4 chips on both the front and back.  Toshiba memory chips were good quality and Mac-compatible, as long as the memory card's design was supported by the onboard memory controller.

Incidentally, Toshiba's THLY25N01C chips used on that SO-DIMM have a 256 Megabit density, so it would take 8 chips on the card to produce 256 MegaBytes of memory.  If it does have 8 chips (4 chips on both the front and back), the internal organization may not be supported or the SO-DIMM may be damaged.  You should try another.

Data Memory Systems web site says PC66 memory

http://www.datamemorysystems.com/apple-imac-g3-233mhz-bondi-blue-m6709ll/am6709l l/b-original-rev-ab-memory-upgrades/

• STANDARD MEMORY: 32MB or 64MB
• MAXIMUM MEMORY: 384MB or 512MB
• NUMBER OF SLOTS: 2
• MEMORY TYPE: PC66 SDRAM SODIMM

Disassembly instruction...

https://www.ifixit.com/Guide/iMac+G3+Model+M4984+RAM+Replacement/1500

Note the last line, "The iMac supports two pieces of PC66 laptop RAM, though it can use PC100 and PC133 (laptop size of course)."

Web page with 128 meg chips,

http://www.datamemorysystems.com/synchronous-dram-memory-upgrades/