# DDR3 Ram Voltage?



## techguy31 (May 28, 2010)

So I recently bought a mobo (gigabyte ga-p55-usb3) and had some questions about the voltage of the ddr3 slot for the mobo.  I bought a --> A-DATA 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1333 recently.  It has 1.5 voltage.  what if I purchased one with that had 1.55V - 1.75V how would I configure it in mobo should I put it on auto or something?


----------



## techguy31 (May 28, 2010)

And what is the timing and cas latency?  Do they have to match the mobo's spec?


----------



## techguy31 (May 29, 2010)

Can anyone help with this?


----------



## Asylum (May 29, 2010)

Just check your mobo's spec's on compatable ram for it.

You can set voltage and timings for your ram in the bios.

The ram should have what timings and voltages it is capable of doing.

Use CPU-Z and click the SPD tab and it will tell you also.


----------



## Tatty_One (May 29, 2010)

If your talking about mixed voltage sticks, most 1333mhz ram sit around 1.5V anyways, if you got some that was rated at 1.55V then you would need to set the lot (beacause there is only 1 VDimm setting) at 1.55V but thats OK, normally there is a good bit of headroom, you will struggle to find anything 1333mhz that needs 1.75V to get there, unless they were at 5-5-5-15


----------



## cadaveca (May 29, 2010)

techguy31 said:


> So I recently bought a mobo (gigabyte ga-p55-usb3) and had some questions about the voltage of the ddr3 slot for the mobo.  I bought a --> A-DATA 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1333 recently.  It has 1.5 voltage.  what if I purchased one with that had 1.55V - 1.75V how would I configure it in mobo should I put it on auto or something?


This ram may need anything from 1.55v to 1.75v(if you are refering to sticks that offer this broad range of voltage), depending on the motherboard it is installed into. If 1.55v doesn't work, you may continue to increase the voltage up to 1.75v, and still be within warrantied values. Otherwise, it's not recommended to mix and match memory, as excess votlage can lead to excess heat, and can affect that stability of the sticks.



techguy31 said:


> And what is the timing and cas latency?  Do they have to match the mobo's spec?



Timings are speed settings seperate from the bus speed. Different operations, such as writing and reading, require different lengths of time to complete fully, as well they set a bit of time to change from one operation to another. This changes depending on IC, and the bus speed these operations take place on.

CAS Latency is the time from when the controller requests data, and how long it takes the memory to make that data available. In 7-7-7-21 timings, the first number 7 is CAS Latency.


----------



## techguy31 (May 30, 2010)

If I have option for auto for the voltage config in my mobo should I use auto to let it configure itself?


----------



## overclocking101 (May 30, 2010)

you can but often boards either over volt or under volt. its best to set it yourself. on P55 you can go anywhere from 1.5v to 1.7v and be withing the reccomended voltage range, so if your 1333mhz sticks are rated at 1333mhz 7-7-7-20-1T @1.4v you can probably do 1.65v 1333mhz at 6-6-6-18-1t OR 1600mhz at 8-8-8-24-1t OR 1550mhz 1.65v 7-7-7-20-1t the range broadens with better ram. if you are talking about mixing ram, ie you have a kit of 1333mhz 1.5v and you want another kit but the one you want states 1.55/1.75 you should be fine.


----------



## cadaveca (May 30, 2010)

techguy31 said:


> If I have option for auto for the voltage config in my mobo should I use auto to let it configure itself?



That really depends.

OK, so, there is a "board" of all these companies that use memory. Together they decide what becomes the "standard". This "board" is called JEDEC.

All memory sticks conform to some sort of JEDEC spec. Choosing "auto" will only provide you with JEDEC operation.

JEDEC just recently decided on 1600MHZ specs. However, for a long time, we have had memory at this speed or greater, and right now, 1600mhz seems to be the norm.

However, at the same time, both Intel and AMD only actually support, officially, JEDEC specs, and because of JEDEC just recently deciding on 1600mhz, there's nothing from Intel or AMD that supports greater than 1333mhz. Offically.


Now, yes, MOTHERBOARD MAKERS says that you can get more than that 1333mhz, but just so you know, officially, this is overclocking, and voids your processor's warranty. Of course, AMD or Intel denying a RMA becuase of running greater memory speeds than is not very likely, but legally, it's more than possible.


As well, the limitations imposed on memory speeds by AMD Phenom2 cpus is directly due to JEDEC specifications...they could make a controller that's faster, easily. Take a look at Thuban...

So, before I can answer that question, you must decide what you are trying to do...running rated memory speeds...running rated controller speeds, or even outright overclocking are all posibilities that must take a different approach.


----------



## techguy31 (May 30, 2010)

cadaveca said:


> That really depends.
> 
> OK, so, there is a "board" of all these companies that use memory. Together they decide what becomes the "standard". This "board" is called JEDEC.
> 
> ...



Basically I am not overclocking anything.  I just want to plug the rams into the gigabyte p55 usb3 which says the voltage is 1.5.  I am not overclocking anything that's the reason I got the 1333 mhz.  
Thx for the reply.


----------



## cadaveca (May 30, 2010)

techguy31 said:


> Basically I am not overclocking anything.  I just want to plug the rams into the gigabyte p55 usb3 which says the voltage is 1.5.  I am not overclocking anything that's the reason I got the 1333 mhz.
> Thx for the reply.



For that 1333mhz, JEDEC spec says 1.5v. JEDEC also has a low-power spec, but basically all modules on the market today will do 9-9-9-27 @ 1333mhz and 1.5v, and in fact most will do more that that performance wise(hence 2400mhz sticks available on the market, yet no JEDEC spec above 1600mhz).


There are many DDR3 parts that won't...but they are pretty old, so as long as you are buying from a retailer with a fair amount of sales, you need not worry about that part.

Mixing DIMMs @ JEDEC specs should not be much of an issue...as long as you make sure that each memory channel is loaded the same way. If you put different IC's in each channel, there's a very good chance you'll at the least have stability issues, if not a complete lack of booting.

HOWEVER!!!

Memory ICs from differnt memory makers are very different from one another. Micron, Samsung, Elpida, Infineon, etc, are memory makers. OCZ, Corsair, Mushkin, etc are NOT....they are merely DIMM assemblers..some use thier own pcb, of course, but none of those places own foundries nor design the actual memory itself.

Because they buy the bits and put them together, and the market part count is purposely kept close to supply, these guys buy parts from all of the makers, and over time, even though a stick may have the same part number, it may not actually contain the same memory on the PCB.

This is why we have "matched pairs" and "matched sets", and these companies do not guarantee buying two sets, and having stability...

If you mix the wrong ICs together, again, you might not even be able to boot.

So, again, ther is no clear answer to your question, without getting more information.


----------



## techguy31 (May 30, 2010)

Thx for the insight man...


----------



## cadaveca (May 30, 2010)

Sorry I cannot give you an exact answer, but in that situation you ask about, there isn't a clear answer...even OCZ, Corsair, et al can't answer that unless you buy two set from the same maker, and the maker does the work and checks serial numbers to confirm what bits the sticks are made up of...and most won't do that for the end user like us.

Corsair is the only assembler I know of that clearly states what's in each of thier sets, and regularily updates that list. That lone fact is why I will only buy from them now...because the industry as a whole does not sell parts with enough performance for my needs, and overclocking is a must for me, so I need to know exactly what I'm getting.

Any time I see a forum rep telling a user they cannot disclose what IC is in thier sticks, I cringe, and note to never buy from them.


----------

