DDR2 Memory Voltage question (1.8v vs. 1.9-2.1v)

[jrichrds]

I see DDR2 memory modules that specify 1.9v-2.1v instead of the standard 1.8v. It seems quite typical with DDR2-800 and faster.

Do these require motherboards with manual voltage control for memory? Or is the required voltage automatically detected and applied?

Conversely, what has been your experience with memory modules that specify 1.9v-2.1v running on motherboards that only support 1.8v? Will it be unstable (or not run at all), or do most of them contain SPD data for running at 1.8v with slower timings?

 

[BlueAcolyte]

Most motherboards will just boot at 1.8V, so you'd have to fix it yourself. RAM that is JEDEC standard, however, will run at 1.8V, possibly at a slower speed.

 

[n7]

Originally posted by: jrichrds
I see DDR2 memory modules that specify 1.9v-2.1v instead of the standard 1.8v. It seems quite typical with DDR2-800 and faster.

Do these require motherboards with manual voltage control for memory? Or is the required voltage automatically detected and applied?

Generally they need vdimm to be set manually.

Originally posted by: jrichrds
Conversely, what has been your experience with memory modules that specify 1.9v-2.1v running on motherboards that only support 1.8v? Will it be unstable (or not run at all), or do most of them contain SPD data for running at 1.8v with slower timings?

All DDR2 should have SPD with 1.8V support, so they will usually boot up fine (albeit at slower speeds/looser timings) @ 1.8V

If your motherboard doesn't support manually altering vdimm to over 1.8V, you'd likely want to look for RAM that is designed for 1.8V operation.
Or at least be able to modify speed/timings to run well at that speed.
Again, usually RAM will have SPD that allows for running at that lower voltage, but when it comes to enthusiast level RAM, you should always be aware some manually application of settings may be needed.