Hi there, I installed 4x1GB ddr2 hynix 6400 800mhz memories onto my optiplex 620. Yet the system and bios both only shows that the memories operating at 533mhz. All four memories are identical and all four memories are the exact same type. Is it a limitation of the Optiplex 620's chipset which means it will only run at 533mhz no matter how much higher mhz your ram sticks are?
That's a 13 yr old computer. It is doing the best it can. That is the max it can recognize.
There are four memory connectors on this motherboard which hold 533MHz and 667MHz DDR2 SDRAM memory model. It, being a desktop and not a server motherboard, uses a non-ECC type of memory. It holds a minimum of 256mb single sided RAM or 512mb double sided RAM array. It will accept a maximum of 4gb of memory.
Your motherboard probably isn't recognizing the ram as capable of 800MHz and chose a default. If you want to utilize 667MHz, it would have to have the correct ram.