memory upgrade

Both the specs on the i945 express chipset and the users guide for the Optiplex GX620 USFF says it will support PC2-667. Are you saying that the Bios didn't recognize the speed change?

Because since it is not supported it will only run at slowest speed that the memory has programed into it.  Memory if it posts and is not recognized by the bios will fall back to default settings.

Hi dansavage,

Your Optiplex specifies DDR2 PC2-5300, which should have an I/O bus clock speed of 333 MHz. So something is definitely not right. What is the make and part number of the new RAM? Did you purchase a matched set of 4x1GB modules?

I have 2x2GB Avant  AFV6456U61E5667F7 one is -WBXP the other is -MTGP.

So can you suggest why it is still running at the 533 MHZ speed. i have updated the bios to the A11 version of dell Bios.

Correction: AVF6456U61E5667F9

Crucial the most recommend memory for Dell systems says it will only support 4 GB of PC2-5300 memory.

The letters would be revision information by the vendor. My next thoughts is voltage requirements for the sticks.  Dells are very finicky with memory.  

go to the SPD tab on CPUZ and look at the JEDEC listings. compare those numbers to the vendors specs.

dell memory vendor specs or avant

Then it is because the memory is mismatched. You stated previously that the numbers are different. Any mismatch in memory modules will cause the memory controller to become confused and it will throttle down to the slowest speed.

This is why is it important to buy the memory all at once in matched sets.

There are programs in each memory stick call SPD's these are programed by the manufacture and contain the operating parameters that the memory controller will read to utilize the memory in the system. And since manufactures will tweak these settings to enhance memory performance and stability across platforms any change between sticks will result in a mismatch as far as the controller is concerned

Each stick reports 266.1 MHZ memory speed  pc2-5300 (333). the only difference between the two sticks is the letters at the end of the part number. The bios still reports a 533 MHZ memory speed.

This report came from CPUZ version 1.60 X64

Try running with just one stick installed and see what it reports. I would do this with each stick. If each stick by itself works then you have a mismatch.

avant

The memory tab reports CL 4.0 clocks, tRCD 4 clocks,tRP 4 clocks,tRAS 12 clocks, tRC 16 clocks. FSB:DRAM 3:4, DRAM frequency 266.3 MHZ JEDEC #2