Matching 2x16gb kits, opinions?

[hp9000]

Hi,

I currently have an Asus P8Z77-v Pro motherboard. I'm thinking of getting 32 Gb RAM and I'd like to know what your experiences are with regards to buying 2 kits x 16gb like these (http://www.newegg.ca/Product/Product...82E16820231528, on special today) vs. a single 32gb kit. Would you recommend spending the extra money for the 32gb? Could I run into problems by mixing 2x16gb, even though they're the same model, timings, etc? I've heard that there may be problems with XMP, etc. but I don't know enough to be able to tell. Is there anything built-in that will let a module know that they're working with "sibling modules" as opposed to 2 separate kits?

Thanks!

Gabe

[Tradesman]

Yes, ANY time you mix sets it can be problematic, even with the same exact model. Generally it starts to get problematic at 1600 and up, and also more likely the higher the density of the sticks Least likely with 1GB stick, most likely with 8GB sticks. In part the problem comes with XMP which is programmed by the set (1, 2, 3, 4 sticks etc) so when you mix two sets that advanced timings are there, but for a two stick set, as an example a 2x8GB set might have a tRFC (one of the advanced timings) of 171 while for 4 sticks (or 2 sets) it might require a tRFC of 278 or more...XMP simplifies things by 'telling ' the BIOS the proper timings as well as what voltages are needed, if the CPU requires an OC etc. By mixing you should be familiar with setting up DRAM and the system manually....and even then you might get two sets that just won't play together, where with a single set, they are tested to work and are programmed with the needed settings.

[hp9000]

Thank you so much! I didn't know anything about the tRFC settings. See, in comparison, the answer that I got for the same question on the newegg forum:

It doesn't matter. Both are the same. you just wanna make sure that it's 1.5V. DDR3 1600 is the sweet sport right now. Above that costs more with no appreciative performance gain in reality. They can be the same or different brands just like you can use 1 Duracell and 1 Energizer for an equipment that reuiqres 2 batteries. You want short heatspreaders if you want to install an CPU air cooler and overclock the CPU (the GSkills are barely fine).

So you've saved me a possible headache. I'll wait until a good 32gb kit goes on sale and get that, then.

Thanks again!

Gabe

[Tradesman]

No problem, what you quoted from the Egg is one of the reasons so many people run into problems, what he describes, same freq, timings, etc is how things were to a large degre back with DDR2, and is to an extent today with low freq/low capacity sticks/sets, but you look at DDR3 today, when the original specs for DDR3 came out they were looking primarily at RAM running up to 4x4 GB sticks of 1600 and there now 8x8GB sets and running up to 3000 or so....and there's very few folks out there that are very comfortable in setting up advanced timings, most folks want to just enable XMP and be done, sadly with the high freq/density sticks, most of the mobos aren't ready for these sets, the mobo makers didn't (and to a degree, still haven't) accepted that there are a ton of people out there that want to run 32 and 64GB of fast DRAM

[hp9000]

Thanks again! If I may ask one more question: since they are about the same price, what's faster: 1600 cl 9 or 1866 cl 10? I've seen that the higher the Mhz, the higher the latency and I'm left scratching my head as to what's faster, or if it even makes any difference. To give you some context, I use Oracle databases and Virtual machines, which usually require tons of memory.

Thanks!

Gabe

[Tradesman]

Of these two sets the actual 'performance' is about equal, the main difference is that the higher freq, 1866, will provide wider bandwidth or you'll have more MBs of reads/writes per second, but the time of the cycles of operation are near equal. (needless to say it's sort of hard to explain without getting rather technical) but basically the higher the freq, the higher bandwidth.

I like high performance sticks so in general I look at things like (freq/CL) 2400/10 then 2133/9, 1866/8 on downward....with the examples you show (for comparison shopping I'd look at 1333/8 then 1600/9, 1866/10, 2133/11, etc. so if shopping based on this and the two are the same price, definitely the 1866, but if you find a 1600 set at the same price with a CL of 8 or better yet 7 the the 1600 set is the better price as the cycle for cycle rate will overcome the bandwidth advantage by doing more cycles - if that makes sense to you

[hp9000]

Thank you so much, you've been a great help and I've learned quite a bit! I'll probably bug you again in the future, though

Gabe

[Tradesman]

No problem, glad to help, might take a look in the General Discussions forums, I put up a few info threads on different things you might find of interest.......thanx for the comments, appreciate it