Difference between DDR3 PC3-10700 and PC3-10666 memory

[xscess]

I need help deciding which memory to buy to add in to HP Pavilion 580t desktop PC. Right now it has 12GB triple channel DDR3 PC3-10700 (6 x 2GB) in it, and I would like to make it either 16GB (4 x 2GB + 2 x 4GB) or if it has to be "triple" then, 18GB (3 x 2GB + 3 x 4GB) please.

Now while searching for PC3-10700, I could only find 10600/10666, so can I use 10666 along with 10700?

So far I have narrowed down to:
-- G.SKILL 8GB (2 x 4GB) DDR3 1333 (PC3 10666)
OR
-- G.SKILL 12GB (3 x 4GB) DDR3 1333 (PC3 10666)


Many thanks in advance.



Desktop specs:
Link to CPU-Z txt report: filedropper.com/pavillion580t
Processor: Core i7-970
Motherboad: Pegatron 2A86
Memory: 12GB Triple Chanel DDR3 PC3-10700 (6 x 2GB)
Graphics: GeForce GTX 460

 

[Blastman]

Now while searching for PC3-10700, I could only find 10600/10666, so can I use 10666 along with 10700?

PC3-10700 = 10600/10666

PC3-10700 … that's either just a typo or someone called it 10700 by rounding 10666 up to 10700. Just like the HP site names PC3-10666 as PC3-10600 by rounding down.

 

[xscess]

@ Blastman

Many thanks for the reply. And what about "triple" channel? Could I have 16GB as describe in my earlier port or does it have to be 18GB...

Thanks again.

 

[Deders]

Just wondering what you use that requires more than 12GB?

You could probably have 16GB in 2 channels but for bandwidth it would be better to go with 3. Not sure if the X58 supports having triple channel with different size sticks, you might have to go with 24GB.

I should note that when you use mismatched sizes on dual or triple channel motherboards, not all the memory will work in dual/triple channel mode. For example, 4GB+2GB in matched slots will work in what's called hybrid mode rather than full dual channel, because one channel has 2GB more. You get slightly less memory performance in hybrid mode but it will only really show up in memory benchmarks and real world performance will be fine. Basically it should be unnoticeable from full dual/triple channel mode.

Wasn't that implemented on later generations?

 

[Blastman]

You can use either 16GB (4 x 2GB + 2 x 4GB) or 18GB (3 x 2GB + 3 x 4GB) no problem.

I should note that when you use mismatched sizes on dual or triple channel motherboards, not all the memory will work in dual/triple channel mode. For example, 4GB+2GB in matched slots will work in what's called hybrid mode rather than full dual channel, because one channel has 2GB more. You get slightly less memory performance in hybrid mode but it will only really show up in memory benchmarks and real world performance will be fine. Basically it should be unnoticeable from full dual/triple channel mode.

edit: It's called flex mode, I called it hybid mode.

 

[Blastman]

Wasn't that implemented on later generations?

That's an interesting point. I didn't think so, but I checked and X58 boards are listed here intel.support so it would seem to apply to triple channel boards based on X58.

 

[Deders]

It would seem that Flex mode was introduced back in the later LGA755 boards so yeah it should be fine, but 6GB of it would not be triple channel.

 

[xscess]

@ Blastman & @ Deders Thanks alot guys.

Just wondering what you use that requires more than 12GB?

I have a system with 4GB PC3-10700 memory, so I wanna move 4GB (2 x 2GB) out of this PC with 12GB, and add some more to it. Besides this, usually I have 2 or so VM running most of the time on this PC.

Now if I go with 18GB, it should be like... first 3 slots with 4GB each and rest 3 with 2GB each, correct?

 

[Blastman]

Now if I go with 18GB, it should be like... first 3 slots with 4GB each and rest 3 with 2GB each, correct?

Ya, you could do 444-222 but you might be better going 442-422. That would mean the first 8GB and last 4 are running in full dual mode. Not sure it would make much difference, but it might be slightly better.

Or even maybe 424-422, that would mean the first 12 or 16 GB (? Not sure) is running in dual channel.