1.8volt or 2.1 Volt for CM2x2048-6400C5DHX? Please reply quickly?

My Corsair memory (2x 1GB kit) lists 1.80 V vert.1 on the

front of the package - CM2x2048-6400C5DHX

This link lists the voltage for the CM2x2048-6400C5DHX

as 1.8 volts. The C5DHX is the 7th one, counting up from the bottom

of the page.

http://www.corsair.com/configurator/product_results.aspx?id=543673#other_modules

However, in my thread here:

http://forum.corsair.com/v3/showthread.php?t=79179

RamGuy says this:

"Corsair TWIN2X2048-6400C4DHX DDR2-800 (XMS2-6400C4)

Corsair TWIN2X2048-6400C5DHX DDR2-800 (DHX2-6400C5)

Either set will run with that MB and the C4 part is the faster of the two modules. But the MB memory Voltage will have to support being set to 2.1 Volts to support these modules."

So which is the proper voltage for the C5DHX?

The C4DHX is listed at 2.1, but the C5DHX, just below, is

listed at 1.8 volts.

Planning to install everything, starting this afternoon,

so I would deeply appreciate quick replies.

Thanks very much!

In otherwords, two different voltage settings for two different products.

While yes, they both run at the same timings, they're of different sizes and therefore use different ICs which have different voltage requirements.

Everything is assembled, EVGA 750i FTW POSTs fine,

memory works fine too. Memory settings are auto for now

- stock voltage on 750i Dimm slots is 1.8 volts.

Just have to reformat Windows again.

I appreciate everyone helping out a newbie!