Example form Newegg...

Crucial 184 Pin 512MB DDR PC-2700 16T - OEM

This is just a guess, but I think that's the access time. 8T would be 8ns, 16T would be 16ns.

Again, that's just a guess, I may be way off..

Actually for Crucial RAM specs, the 4T 8T and 16T refers to the number of chips on the PCB. Usually 4T and 8T has chips on just one side (single sided), although very rarely 8T can be double-sided.

16T is double-sided with 8 chips on each side of the PCB.

8T 16T, etc. in a computer's bios refers to particular RAM timing settings.

The example you gave is a RAM module which has 16 chips on it.

Edit- you can see this by looking at these images : 4T (http://www.newegg.com/app/Showimage.asp?image=20-145-497-01.JPG) and 8T (http://www.newegg.com/app/Showimage.asp?image=20-145-001-04.JPG)

RAM timings are fun, aren't they? :p They are often listed as a string of numbers, such as 2-2-2-6T. The first refers to the CAS latency, and the "T" number refers to the RAS latency. I don't think that has ever been as high as 16T, but 8T and maybe even 10T have been made.

Told you I was just guessing :D

Ram timings are fun, the T I was referring to was the DRam Idle Timer, which on my P4P800 (865PE) board is indeed set to 16T. Options for Infinite, 0T, 8T, 16T, .....64T, Auto.

Ah, that setting refers to the number of clock cycles between the RAM modules' page refresh. Since this is synchronized with the bus speed (a prerequisite of being Synchronous DRAM) I recommend most people leave this at the default setting. ;)

However, if you overclock and you know what you're doing (I hope both are true :p) then go ahead and fool around with this setting. Just a word of advice - if you change this setting, make it bigger not smaller!

Cool, thanks!

Now, is there any reason to buy one vs. the other, all other specs being pretty much the same? Including price.

ie: Crucial 184 Pin 512MB DDR PC-3200 8T - OEM vs.
Crucial 184 Pin 512MB DDR PC-3200 16T - OEM

My inclination would be to go with the 16T (double sided) if your motherboard is relatively new.

You can go to Crucial's website (http://www.crucial.com/) and select your motherboard manufacturer and model number to determine exactly which modules are compatible.

I think you mean 8T, malcore. ;) Single-sided sticks of RAM use higher density modules, which are much more likely to work in newer mobos.

There's also a slight memory subsystem advantage to using higher density RAM modules, as well as fewer sticks of RAM. Nothing really noticeable, mind you, but it exists nonetheless.

Have to disagree with you (slightly) on that one saph :

double sided vs. single sided on Intel 875/865 chipsets (http://www.anandtech.com/memory/showdoc.html?i=1839&p=4)


From Tom's Hardware:

Single and double-sided modules are another source of confusion: on principle, double-sided RAM modules are faster than single-sided, as they can keep twice as many memory pages open.
However, most RAM modules currently sold have chips on one side. There is often confusion here, too, as many manufacturers place the chips on both sides - to enhance the layout - although the module is actually single-sided. In our experience, the double-sided technique provides between three and four percent more performance.

From here (http://www20.tomshardware.com/motherboard/20030519/i875p-03.html)

So, in essence, 16T may only mean there are chips on both sides, not necessarily "double-sided".

The issue is definitely not black and white.

Hmmm... that's a bit of a change from regular SDRAM. With SDRAM, higher density modules made for a faster system because the hit percentage was higher. I guess DDR works differently enough that this is no longer true (or it could be the much higher speeds :D).

Thanx for the heads up, malcore. Filed away.