Educate me on Memory?

[Ember1205]

Hi, All.

I seldom find myself in the situation of needing to purchase memory. When I do, however, things have changed enough that I have to re-learn everything. And, that's where I'm at.

I need to purchase some DDR3 RAM (4 8GB sticks) for an HP computer, and there's a LOT of options that are making chasing down the right stuff a little tough.

Buffered / Unbuffered?
ECC / Non ECC?
CAS Latency?

The machine specs DDR3 10600 or 12800, and I believe this is indicating the power consumption of the memory sticks (10600 being low power). True? Does this matter?

The motherboard can handle four DIMMs, up to 8GB each for a total of 32GB. I'm building a virtualization platform, so I need to max out the RAM (there's 12GB in there now (one 8GB and one 4GB), so I'll be replacing one of the sticks (the 4GB) and adding two more 8GB beyond to get to the max RAM.

If anyone can help me understand why Corsair memory is $640 for 32G while many others are about $120 for the same amount, I'd appreciate it.

 

[harryb2448]

Go to your HP specs and check out the precise memory you need. There is differences in density, latency etc.

 

[Raz0rEdge]

Harry is correct, you should first figure out what the exact specs of your computer's memory requirements are. They vary between generations (DDR2, DDR3...DDR5), speeds, and so on..

The difference with buffered (or registered) and non buffered memory deals with additional hardware that is present on the RAM sticks to deal with data access. Buffered memory has, aptly named, buffers that allow a little bit of caching so that electricity load of the RAM stick is reduced. This type of RAM is usually used on servers or system that have large amounts of RAM. Similarly, ECC (error correction code) RAM is something that the motherboard would have to support to ensure data integrity. If your motherboard doesn't have the necessary components, then Non ECC RAM is fine.

CAS latency is VERY important to get right and indicates the time from when a request is made for a piece of data and is available to read. The motherboard (DDR controller specifically) will indicate what is an acceptable value (or range) for this. Having RAM that violates this time will yield random errors that will usually result in app or full-blown OS crashes.

So make sure that you match the speed and CAS latency at the minimum. Using ECC RAM on a system that doesn't have the necessary hardware is a waste of money, but vice versa will yield data errors or worse corruption..

 

[lclev]

More information is needed. Type in the HP model on the HP site and check out the specs. I just refurbished 2 HP workstations at work and both required ECC registered memory - which is more expensive and a must have for that computer. Also pulling one of the memory sticks from the computer might give you the specs. You might get lucky and the memory will have a sticker on it with all the information - or not.


Lisa

 

[Ember1205]

Sadly, I've listed the "specs" already.

There is NOTHING regarding buffered/unbuffered or ECC/Non ECC listed in the specs.

The OEM memory is Samsung, and the label states

8GB 2Rx8 PC3-12800U-11-12-B1

The specs for the OEM memory are:
Speed: PC3-12800 MB/sec
Type: DDR3-1600

 

[Ember1205]

More information is needed. Type in the HP model on the HP site and check out the specs. I just refurbished 2 HP workstations at work and both required ECC registered memory - which is more expensive and a must have for that computer. Also pulling one of the memory sticks from the computer might give you the specs. You might get lucky and the memory will have a sticker on it with all the information - or not.


Lisa

That was how I got what little info I have...

http://h20564.www2.hp.com/hpsc/doc/public/display?docId=emr_na-c03787848

If any of you can make better sense of the minimal info than I could, have at it.

 

[pigoo3]

Go to Crucial.com and use their "Memory Finder" tool. Enter your computers specs…and you will get compatible RAM results. Then you can either order what you need…or read the specs carefully of the RAM that shows up in the results..

Then you will know exactly what RAM you need if ordering from somewhere else.

- Nick

 

[lclev]

Check this out at Crucial:

http://www.crucial.com/usa/en/compatible-upgrade-for/HP-Compaq/envy-700-074

Lisa

 

[Ember1205]

Thanks, Lisa, but I don't think I can "trust" everything that's listed there.

The HP Specs state DDR3-1600 / PC3-12800 or DDR3-1333 / PC3-10600 and the Crucial site shows both DDR3 and DDR3L (I know they're different though I don't know why). Crucial also shows a variety of PC3 speeds including 12800 (supported) and 14900 (not supported directly, although being faster may not be an issue - don't know for sure).

CAS Latency is either 11 or 13, but I don't know what the value is on the OEM memory. The only thing that seems to be constant is that they are all listed as unbuffered and Non ECC.

 

[Ember1205]

I found this:

http://www.devicelog.com/memory/dra...am-pc3-12800u-11-12-b1-2rx8-m378b1g73qh0-ck0/

That's the original 8GB chip with details.

CAS Latency 11
Non-ECC
Unbuffered

 

[harryb2448]

Well try your luck at a HP forum.

 

[Ember1205]

Why? It seems I have found all of the specs... The Crucial site shows a number of memory options that don't match in specs, but I can now easily rule them out.

 

[pigoo3]

The Crucial site shows a number of memory options that don't match in specs, but I can now easily rule them out.

I've always trusted Crucial to supply the correct info. Maybe the computer in question has flexible RAM requirements.

- Nick

 

[Ember1205]

I know Crucial is a good name and they're often looked to for this sort of info. I have no data to refute what they have listed, but I do have to question it since they're showing options that are not listed on HP's web site in the specs for this machine. If those "other" options are "will work" type offerings, I would have expected to see an asterisk or something saying "not an original OEM spec, but certified to work properly" or something.

 

[lclev]

Crucial will list what will work. I have found if you try to use the faster memory options with some picky systems, it may or may not work. I tend to match the speeds. Crucial will take back anything that does not work for any reason but I do understand the object is to get it right the first time.

BTW: DDR 3 is 1.5 volts memory and DDR3L is a lower voltage memory at 1.35 volts which means less power needed. For a desktop you can go with the regular DDR3.

Lisa

 

[Ember1205]

Lisa,

That's what I thought / expected, but Crucial lists DDR3L memory as being compatible with this system. In fact, almost -all- of what they list is the 3L memory with only one or two options being the 1.5Vs DDR3.

 

[pigoo3]

If those "other" options are "will work" type offerings, I would have expected to see an asterisk or something saying "not an original OEM spec, but certified to work properly" or something.

As you said in the beginning of the thread…you're no RAM expert (which is totally ok). Having expectations of seeing an asterisk or "not original OEM spec" may not be the norm.

Trust that Crucial.com knows more than you or I (at least when it comes to HP RAM). And if it should not work…return it.

- Nick

 

[Ember1205]

Knowing that the spec for my motherboard calls for 1.5V RAM is Crucial is predominantly suggesting 1.35V RAM, would -you- trust them in this case? It would seem to me that the RAM would get fried from an over-voltage situation.

 

[lclev]

Low voltage means it will only pull 1.35 instead of 1.5. The motherboard will supply up to 1.5V, but since the memory only needs 1.35V, that is all it will pull. I think you would feel better getting the 1.5V though.

I do a lot of custom PC building and refurbishing older PCs at work. I have found if the PC will boot with the memory and runs with it, it is compatible. The only other issue would be if the memory is bad, which if it is new and from a reputable vendor, you can get it replaced.

Lisa

 

[Ember1205]

So, the voltage is variable to the memory? If that's the case, then the low-power / lower voltage RAM would work.

I wonder why HP doesn't list that as an option in their specs...