RAM HELP (UDIMM versus all other types)

[tinywolves]

I am very confused about these types of rams and google really isn't helping me so I thought I'd ask.

I've only recently build a computer, everything went smoothly but I just don't understand the difference between particular ram types.

What is UDIMM ram?

Say I have this ram
http://poweredbymushkin.com/index.php/component/djcatalog2/item?id=8:994057&cid=5:redline
16GB (4x4GB) DDR3 PC3-12800 7-7-7-24 Redline
1600ghz

And this one
http://poweredbymushkin.com/index.php/component/djcatalog2/item?id=736:997102&cid=5:redline
16GB (2x8GB) DDR3 UDIMM PC3-12800 8-8-8-24
800ghz

Now I know that the tighter latency the better, and 1600 is better than 800?

I just am confused between these and want an explanation.
Do they make UDIMM mem with tighter latency and higher frequency?

 

[Tradesman1]

UDIMM and RDIMM are terms normally associated w/ server DRAM the difference being U=Unregistered or unbuffered and R=Registered...The Unbuffered DRAM is what is usually used in PCs....The 8-8-8-24 set is a 1600 set - the 800 may be typo or with them referencing UDIMM may be as a draw for this particular page to the Server crowd - in honest the sticks are a true freq of 800 but are more commonly referred to as 1600 as that is the effective freq since with DDR being DOUBLE Data Rate, you take the true freq (800) x 2 to get the effective freq (1600). You can take another look at the set on the Egg

http://www.newegg.com/Product/Product.aspx?Item=N82E16820226380

where you won't see any reference to UDIMM, it's just stock PC DRAM

Hope this helps, can go further, but unless you are dealing with high end servers, it would be sort of pointless

 

[Legohouse]

Hello,

Well, Could you let me know your motherboard model number (or system model) and the CPU model? I can confirm if any of the memory which you have listed is compatible with your system only if you could provide me with the info I need.

Unbuffered memory (UDIMM) is faster than registered memory. The register in registered memory delays all information transferred by one clock cycle, slowing the overall system performance. Most systems are designed to take either registered or unbuffered memory. There are two types of Unbuffered memory - Non-ECC and ECC. IMO, UDIMM is mostly used to refer unbuffered ECC but it is also used for non-ecc.

There are various latencies for a specific Frequency, in your case DDR3-1600MHz has 4 latencies namely CL8, CL9, CL10, CL11 and not all latencies are tighter and that's the reason why the lowest CAS latency is recommended. Performance can be increased by decreasing latency and/or by increasing bandwidth. But it is very effective when they are combined like using higher bandwidth memory with the lowest latency possible. As far as I've seen as the frequency gets higher, the latencies also increase, eg. DDR3-1600MHz has a lowest latency of CL8 while DDR3-1866MHz has a lowest latency of CL10 (referring wikipedia) which is increased by 2. I think they are manufactured with higher frequencies and the corresponding latencies which are ordained to the particular frequencies based on the JEDEC model. Hope that helps.

 

[Tradesman1]

Legohouse

Sounds like you are talking JEDEC specs, there's at least 3 manufacturers that come to mind that make high performance 1600 DRAM at CL7 (Corsair, GSkill and Mushkin), and 1866 is spread from CL8-CL11 with CL9 being the most prevalent as far as different sets available, many manufacturers come to mind - at least a half dozen

 

[Legohouse]

Legohouse
Sounds like you are talking JEDEC specs, there's at least 3 manufacturers that come to mind that make high performance 1600 DRAM at CL7 (Corsair, GSkill and Mushkin), and 1866 is spread from CL8-CL11 with CL9 being the most prevalent as far as different sets available, many manufacturers come to mind - at least a half dozen

Yes, I was referring to JEDEC specs for this one. But yeah, I'm aware of these latencies which you have mentioned but thanks for reminding. :jap:

 

[Tradesman1]

No problem, the problem is JEDEC can't keep up with the industry, so even though they set the 'official' standards, there are no real standards, the DRAM manufactures just take things up in steps. Initially DDR3 was only to run up through 1600, that was the expected high point (by JEDEC) and look at it now there are 3000 sticks out there (and higher to come)....and....they are dragging their feet on DDR4

 

[vie_charlie]

Hello,

Well, Could you let me know your motherboard model number (or system model) and the CPU model? I can confirm if any of the memory which you have listed is compatible with your system only if you could provide me with the info I need.

Unbuffered memory (UDIMM) is faster than registered memory. The register in registered memory delays all information transferred by one clock cycle, slowing the overall system performance. Most systems are designed to take either registered or unbuffered memory. There are two types of Unbuffered memory - Non-ECC and ECC. IMO, UDIMM is mostly used to refer unbuffered ECC but it is also used for non-ecc.

There are various latencies for a specific Frequency, in your case DDR3-1600MHz has 4 latencies namely CL8, CL9, CL10, CL11 and not all latencies are tighter and that's the reason why the lowest CAS latency is recommended. Performance can be increased by decreasing latency and/or by increasing bandwidth. But it is very effective when they are combined like using higher bandwidth memory with the lowest latency possible. As far as I've seen as the frequency gets higher, the latencies also increase, eg. DDR3-1600MHz has a lowest latency of CL8 while DDR3-1866MHz has a lowest latency of CL10 (referring wikipedia) which is increased by 2. I think they are manufactured with higher frequencies and the corresponding latencies which are ordained to the particular frequencies based on the JEDEC model. Hope that helps.

Hi Legohouse,

I have a Dell Inspiron 560. It came with 2x Samsung 1GB DDR3 1066MHz non-ECC rams. I'd called into Dell and they have been giving all kinds of advices depending on who i talk to at the local Dell Tech Centre. First, they said just stick to DDR3 Ram would be find. That sounded fishy to me. In any case, i purchased a stick of 4GB Crucial CT51264BA160BJ. It's not working with the motherboard. So i called in again to Dell and they suggested that each slot can't handle more than 2GB. However, corsair's website is recommending a 4GB (http://www2.corsair.com/configurator/new_configurator_corsair_custom.aspx?sc=&id=5360300). It's also possible that same model around different parts of the world or different production batch or place may have different motherboard. I wonder if you can hlep me to make sense out of all these non converging information.

Many thanks!

 

[Legohouse]

Hi Legohouse,

I have a Dell Inspiron 560. It came with 2x Samsung 1GB DDR3 1066MHz non-ECC rams. I'd called into Dell and they have been giving all kinds of advices depending on who i talk to at the local Dell Tech Centre. First, they said just stick to DDR3 Ram would be find. That sounded fishy to me. In any case, i purchased a stick of 4GB Crucial CT51264BA160BJ. It's not working with the motherboard. So i called in again to Dell and they suggested that each slot can't handle more than 2GB. However, corsair's website is recommending a 4GB (http://www2.corsair.com/configurator/new_configurator_corsair_custom.aspx?sc=&id=5360300). It's also possible that same model around different parts of the world or different production batch or place may have different motherboard. I wonder if you can hlep me to make sense out of all these non converging information.

Many thanks!

Hello,

Yes, it's true Dell Inspiron 560 doesn't support sizes above 2GB (4GB, 8GB etc). It supports upto 8GB in total and has 4 slots. Each slot can take upto 2GB only.

Yes, I saw the corsair link and the memory they have mentioned is a 4GB kit (2 x 2GB ) not a single 4GB module, which makes the 4GB kit compatible with your system. Take a look - http://www.corsair.com/en-us/cmx4gx3m2a1333c8

There is a possibility that the motherboards used for the same model around the globe can be a tad different like the manufacturer or some minor change but still they would be supporting the same specs as the earlier versions unless DELL says otherwise. Hence, I don't believe there would be any major changes like supporting more memory or latest processors etc.