Mixed Non-Spec RAM Question

[nomdeplume]

Recently dropped the princely sum of $28 on a business desktop to do some experimenting before I commit to a build. It's a HP 8200 Elite with 2x2GB DDR3 1600(PC3 12800) CL11 RAM that appears stable. The manufacturer calls for DDR3 1333 (PC3 10600) CL9. Helpfully the installed ram has a HP parts number sticker that corresponds with their spec but disagrees with the Micron sticker and CPUZ.

I see that DDR memory's price is skyrocketing so I'd like to bump this up before things get too out of hand. What is the best solution for adding another 8GB or so of RAM, 10600 CL9 or 12800 CL11?

 

[FreedomEclipse]

Pick up some used ddr3 in the FS forum

 

[FR@NK]

Even though that ram is rated for 1600 its only running at 1333. If you need to add more you will need atleast 1333CL9 aka PC3-10600. Are you sure the main board has spare ram slots? Most of these OEM boards only have the bare minimum number of slots.

 

[Jetster]

Doesn't matter, get whatever is cheaper but replace it all with a matched set 2x4

 

[nomdeplume]

CPUZ does show it running at 1333, ie slower than rated. It also shows it running at a latency of 9. Some downgrading is obviously going on. Thought latency was fairly specific but I guess 11 down to 9 works.

MB has 4 slots and max capacity of 32 GB. If I planned to keep it I'd load it up with 4x8GB.

 

[nomdeplume]

Doesn't matter, get whatever is cheaper but replace it all with a matched set 2x4

Simple enough. Thanks.

 

[tabascosauz]

Almost all OEM PCs (at least during the Sandy, Ivy and Haswell eras) were equipped with DDR3-1333 @ C9 or DDR3-1600 @ C11. Don't ask why, I don't know. Aside from it probably being the cheapest solution, 1333C9/1600C11 is by far the most common combination of frequency and timings on the DDR3 market. Disregarding minute differences in the other subtimings, 1333 C9 and 1600 C11 are identical in performance and should be treated as such. However, there is no guarantee that the board will accept 1600MHz.

If you buy RAM as a separate product on the market, you will find that 1600 C9 is usually the starting point. If my memory (ha) serves me correctly, 1600 C9 is roughly on the same performance line as 1866 C10 and 2133 C11 (although as stated before, other subtimings will vary).

In most use cases, you are not losing much by rolling with 1333C9 as opposed to 1600C11, as since I previously stated, the two are virtually the same as far as the stick is concerned (so usually you should not run into instability due to pushing the RAM too far).

Here is a memorable list of priorities when choosing RAM, from an Anandtech article examining memory scaling on Haswell:

I personally feel that as long as you aren't buying timings-prioritized DDR3 (for example, 1600 C7 kits) or frequency prioritized kits (e.g., 2400 C11), you will have no problems with the kit. I am under the impression that even if you buy a 1600 C9 kit, usually the exact combination of 1600 9-9-9-24 (for example) can only be achieved via XMP, which OEM motherboards such as HP's usually don't have. In this case, the kit will simply revert to JEDEC timings, which should be 1600 C11 or 1333 C9.


I ran two sets of mismatched DDR3 for some time in a Dell XPS 8500. One set was 2 x 4GB 1600 C11, the other was 2 x 2GB 1600 C11. Obviously, common sense dictates that this will trigger a sort of asymmetrical memory config which would reduce memory bandwidth to single-channel speeds, but whilst paired with a good SSD, I couldn't tell the difference between it and a "proper" dual-channel setup. I would go for 16GB through either a 4 x 4GB set or a 2 x 8GB set, since 8GB is proving to be more and more meager in the face of Chrome, and DDR3 prices are as you stated, skyrocketing.

Your board has 4 DIMM slots, so it would be capable of accepting a 4x4GB kit.

 

[Bill_Bright]

Make sure you got 64-bit Windows in there or you will be wasting your money.

 

[FR@NK]

Make sure you got 64-bit Windows in there or you will be wasting your money.

Did you even bother to look at the first post?

Looks like a 64bit system to me.

 

[nomdeplume]

Yes, 64 bit W7 Pro and well aware 4GB is the bare minimum it will run on. These computers do have a flex mode to compensate for running different size RAM in the two channels.

"The system will operate in flex mode if the memory capacity of the SODIMM in Channel A is not equal to the memory capacity of the SODIMM in Channel B. In flex mode, the channel populated with the least amount of memory describes the total amount of memory assigned to dual channel and the remainder is assigned to single channel. If one channel will have more memory than the other, the larger amount should be assigned to channel A."

Just to be clear, the mixed non-spec RAM in the title referred to using 2x8 10600 with the 2x2 12800. My simple understanding of RAM lead me to believe this was going to be fine. Better to check though.

Thanks all.

 

[Bill_Bright]

Did you even bother to look at the first post?

It must be nice to be infallible, huh?

@nomdeplume - forgive me for my horrific oversight.

These computers do have a flex mode to compensate for running different size RAM in the two channels.

Note that virtually all motherboards will recognize and run dissimilar RAM just fine - as long as the RAM is compatible with that board. The issue becomes whether the motherboard will run in "dual-channel" memory mode or not. Typically the RAM must have identical specs to take advantage of dual channel (or triple, if supported). As it turns out, dual channel did not turn out to provide the performance boost all the hype suggested. So 8GB in single channel will still provide a significant performance boost over 4GB in dual channel.

 

[nomdeplume]

Exactly, and since I plan to sell this computer sooner than later it may end up being used like that and sold with 12GB installed.