More Slower Ram or Less Faster Ram

[TideBleach]

So I currently built a new computer with a single stick of HyperX Fury Ram at 8 gb and running at 1400 hz, im my old rig (prebuilt) I have an extra 4 gb stick at 800 hz. So My question is, Will it be better to run 12gb of ram at 800hz or 8 gb of ram at 1400hz. And Is it possible to run 3 ram sticks if my mobo has 4 ram slots? Asus B85M-G R2.0

 

[CountMike]

Those things don't add up at all, you better find exact models of RAM you have. To say nothing about it being MHz (Megahertz) not Hertz !
800 MHz will not be same RAM as that 1400 (1333 ?) 800 MHz RAM must be DDR2 and other one DDR3.

 

[nicaragua37321]

One seems to be DDR2 and the other DDR3. DDR3 is faster than DDR2 in almost all situations. So stay with the "1400" (I think you mean 1333) 8gb RAM.

 

[Tradesman1]

What mobo and CPU - model #s of the DRAM would help, the Fury is DDR3 (didn't have any in DDR2)

 

[lordmogul]

We are probably talking about DDR3-1600 and DDR3-2800 here. Since the DDR stays for double data rate, some programs tend to display half that rating.

Some quick calculations:
So the options would be either 8 GB (I assume 2x 4GB) DDR3-2400 in dual channel or 12 GB (3x 4 GB) DDR3-1600 in single channel.
1600 MHZ in single channel has a theoretical maximum bandwith of around 12800 MB/s while 2400 MHz in dual channel has a bandwith of 38400 MB/s
By adding the 3rd stick you basically lowering your bandwith to a third.

Why not go directly for 16 GB (4x 4GB) DDR3-1600 in dual channel with a maximum bandwith of 25600 MB/s. (I'm running 2x 8GB DDR3-1600 and are satisfied with that besides the point that I would need more, but that' not the point here)
Getting a 4th stich with 4GB isn't that expensive today. Just make sure it also supports 1600 MHz and the timings of the other sticks.

 

[Tradesman1]

There are no guarantees when mixing DRAM from different packages - it's a 50/50 crapshoot if they will even play together................................