Is there a real advantage to pick a 1.5v kit over a 1.65v one?

[PODxt]

Hi, I'm about to buy a PC3-12800 16GB RAM kit but one is working at 1.65v for $180 and the other functions at 1.5v for $220.

Is the 0.15 voltage difference between those 2 kits really worth $40? My objective here is to overclock my sandy bridge 2600k to about 4.5Ghz. I read it could be done quite easily.

So what do you think,
G.Skill RipJaws X Series 16 GB (kit 4x 4 GB) DDR3-SDRAM PC3-12800 - F3-12800CL9Q-16GBXL 1.5V for $220
or
KINGSTON DDR3 PC3-12800 - 4 x 4 GB (16 GB) 1600 MHz - HyperX - CAS 9 - XMP 1.65V for $180

 

[Leaps-from-Shadows]

With those two choices, I'd buy the G.Skill kit just on name alone. Plus, I do have the pleasure of running one 8GB kit and one 4GB kit (both Ripjaws X DDR3-1600 CL9) in my Sandy Bridge system.

The Sandy Bridge processors have the same memory voltage limitation as the Nehalem-based processors before them. 1.65v is the maximum you should use.

Depending on the mainboard you use, having all four slots populated with 4GB sticks may necessitate running the RAM at a slightly higher voltage than normal. With the Kingston kit, you have nowhere to go.

However, you would also save some money by grabbing two 8GB kits instead of the 16GB kit. Those quad-channel kits really are for servers that actually have quad-channel memory controllers. As long as you buy two dual-channel kits with the same brand, speed, and timings, you should be good.

You can probably tell what my recommendation is but I'll make it official anyway:
Two G.Skill F3-12800CL9D-8GBXL kits at $100 each for a total of $200.

 

[PODxt]

Thanks for these infos, this is really helping. I didn't know about the voltage limitations
You're right, I'm going to look into 2 2x4GB kits instead of grabbing only 1 kit. I didn't even think about that.

You mention that with some MB I'll have to run the RAM at a higher voltage. I have a regular P8P67, how can I know I'll have to raise the RAM voltage?

 

[Leaps-from-Shadows]

The only way to know for sure is to test it out. If your RAM voltage isn't high enough, you'll likely get the occasional BSOD in normal usage, and you'll get errors in Prime95 and other stability tests.

If you buy 1.5v spec RAM, you would likely only have to raise it to 1.55v or 1.6v to get stable with four 4GB sticks (assuming default 1.5v voltage doesn't work). My 12GB config works at 1.5v with no problems, but I have two 4GB sticks and two 2GB sticks.

 

[bryanl]

DDR3 chips that don't pass all factory testing at 1.50V are deemed defective and are dumped onto the secondary market, where they're bought by module manufacturers with lax standards. That isn't to say all consumer grade 1.50V DDR3 is high quality.

 

[etk]

^+1
1.5V is in JEDEC spec, 1.65 is not. It's like if I gave you a good deal on a new car because it had a bent frame.

There is a large market of people who don't mind running stock speeds @ 1.65 V, but if overclocking is your thing, I would imagine the 1.5V ram would run faster (~1833?) @ 1.65V, wheras the 1.65V Ram has no headrooom