I installed one 2GB DDR2-SDRAM running at 800MHz but when I view the bus speed, it's says it's running at 533MHZ.
It's a Dell OptiPlex GX620 Mini-Tower
Motherboard: Dell 0HH807
Prior to installing the RAM, the motherboard had 512Mb DDR2 SDRAM at 533MHz installed.
I installed the 2GB RAM for a total of 2.5GB RAM but it says both are at 533MHz.
So I removed the 512Mb of RAM in hopes of getting 2GB of RAM running at 800MHz but no such luck.
It also says it's now: DDR, 2048MB, 533MHZ
U mean DELL OPTIPLEX GX620 HH807 motherboard, right?
On the web they say that this mobo is supported DDR2 module ram.
And not mentioned about what FSB on your mobo can support.
Are u sure your new ram is DDR2 type?
Basically, if u inserted 2 stick of ram with different type then your speed is the speed on ram with slower speed, in this case at 533MHz...
Have u tried install you're DDR2 800 on each slot?
800mhz is the *MAX* rated memory speed where as your system needs to run the memory in ratio hence why its running at 533mhz - that is correct, and is the optimal speed.
What you would find is that regardless if the memory could run at 800mhz, 533mhz will perform better because the FSB will not allow that amount of bandwidth through, and the lower timings at 533 would offer lower latencies at the same total usable bandwidth etc.
Also you would be better off with the old 512mb stick removed etc - follow the golden rules of memory - 1) least amount of memory sticks and 2) most matched memory for *BEST* results.
You have no problem, other than you have broken the golden rule of buying memory. Memory should be bought and installed in matching pairs. The speed your memory is running is likely a motherboard limitation.