RAM: What exactly is SPD (serial presence detect)?

[His Royal Majesty King V]

All,

Just got an old Athlon 500 system (a Compaq) from a friend of mine.

Been doing a little digging. Research seems to indicate that this model used an Irongate chipset, but I swore I saw a Via chip where the southbridge chip goes (northbridge had a heatsink over it).

Also found that I'm limited to 384MB on it... I assume that I have to use the low-density stuff.

BUT, what the heck is Serial Presence Detect? Compaq's support site says that the RAM must support this, but how do I know if I have it?

I have SDRAM modules from my socket 7 boards, and I believe I got most of those modules long after the 500MHz Athlon was introduced.

I assume the system will just barf if the RAM is inappropriate, but I'd like to know if I can determine this ahead of time somehow.

Thanks.

[samuraiboy]

your RAM must have a serial # detected... most OEMs use that king of RAM... use HP, Apacer, Kingston, etc....

[georgep1]

SPD means that the RAM has a small chip which carries with it the specifications/timings of that memory. Motherboards can then have settings in BIOS which will read this information from the RAM module and automatically set timings to SPD default values (if you want).

You can run CPU-Z from

http://www.cpuid.com/cpuz.php

to make sure your RAM has this. Go to the SPD tab of the program display and if there are values in the SPD Timings Table, you're good to go.

[flippedgazelle]

SPD=Serial Presence Detect

Nothing to do with any kind of serial number, nor any differentiation between retail and oem, all modern SDRAM uses this to allow the motherboard automatically detect the speed, latencies and precharge/discharge timings of the memory chip.