RAM compatibility.

[A Traveller]

Hi All.

I have just noticed that the RAM which I was planning on buying (DDR3) is rated at 1.8v, however, the motherboard I was planning on buying states 1.5v. I have done a search for this problem on the Internet and this question seems to be quite common. The answers which I have read are usually that the voltage can be changed in BIOS. I checked the motherboard's manual and this is what it says.

DDR3 Voltage Control
Allows you to set memory voltage.
Normal Supplies the memory voltage as required. (Default)
+0.050V ~ +0.750V Increases memory voltage by 0.050V to 0.750V at 0.05V increment.
Increasing memory voltage may result in damage to the memory.

I will not be overclocking and do not wish to risk any damage at all to my pc or its components. The problem is I have briefly browsed various types of memory and the voltages are quite varied; 1.5, 1.9, +2, etc. I haven't come across memory at 1.8v so how exactly does a person choose suitable memory for a motherboard? Am I missing something????

Thanks.

[usually_quiet]

If you really want to play it safe, shop within the recommended memory list for your motherboard. A link for that is usually found on the manufactuer's website on the specifications page for the motherboard. or on the support page for it.

[stiltman]

If you really want to play it safe, shop within the recommended memory list for your motherboard. A link for that is usually found on the manufactuer's website on the specifications page for the motherboard. or on the support page for it.

That is a good recommendation especially for Intel Motherboards. They can be VERY picky when it comes to RAM

[redwudz]

With DDR3 RAM, 1.5VDC appears to be the default voltage. With DDR2, it was 1.8VDC. Some RAM uses higher voltages for stable operation and those are usually higher performance RAM modules. Some DDR2 modules use voltages up around 2.2VDC, and not all motherboards can go that high. That type of RAM is usually designed for overclocking. If the manufacturer rates the RAM for that voltage, you can safely use it. But higher voltages usually mean more heat. If you don't plan to overclock the RAM, I would use RAM that performs at the motherboards default voltage. Performance RAM may run at the default voltage if it's not overclocked, but then again it may not, at least properly.

Best is to use usually_quiet's advice and look for RAM recommended by the motherboard manufacturer. Although some MB manufacturers will list RAM that may not be easily available. Or it may be RAM that the RAM manufacturer has paid the MB manufacturer to list. You can at least check with one of the major RAM manufacturers and see if your motherboard is listed with them and use RAM they recommend. And I would only buy RAM with a (Limited) lifetime guarantee. If it fails, it will be replaced.

[A Traveller]

Thanks for the replies.

I followed the advice given and checked the voltage of a few of the memory modules that appeared on the motherboard's supported list and the few I checked included 1.9v memory. Can anyone explain why this would be? Some memory I came across stated VDDQ = 1.5V ± 0.075 but also quoted the voltage as 1.9v.

I also went onto a website and looked for the cheapest possible RAM, which was 256Mb 133Mhz Value Ram. This had a voltage of 3.3v! So does that mean that a new, modern motherboard cannot use this cheap, low end memory?

The motherboard is an AMD one.

I checked Kingston's website and the highest RAM listed for the motherboard was value ram at 1333MHz. I wanted at least 1600 as the motherboard is capable of 1666.

Why is there such a large variation in RAM voltage???? Why does 1.9v RAM appear on the motherboard's list and the following statement in their user manual???? "Increasing memory voltage may result in damage to the memory."

I'm totally annoyed now.

[MOVIEGEEK]

Thanks for the replies.

I also went onto a website and looked for the cheapest possible RAM, which was 256Mb 133Mhz Value Ram. This had a voltage of 3.3v! So does that mean that a new, modern motherboard cannot use this cheap, low end memory?

Very unlikely, besides the voltage being different SDRAM only has 168pins. They were used with AMD Duron and Intel PIII.
Go to www.newegg.com and use their memory configurator.

[redwudz]

They always warn you that increasing the RAM voltage may damage it. But if it's rated for that voltage and has a guarantee, not a big problem as you aren't really increasing it, you are putting it at the manufacturer's default RAM voltage. The DDR2 RAM I use in one computer is rated for 2.1VDC and that's what I run it at. The manufacturer garantees it will run at voltages up to 2.5 volts, but I don't need that as my overclock isn't high enough to need a increase in RAM voltage for stability.

If you want performance and stability, I would stay away from 'Value RAM'. Get a good brand, Mushkin, OCZ, Crucial, Corsair, or others with heat spreaders and a lifetime warranty.

What motherboard and CPU are you using? With DDR3, some use a triple channel RAM setup with three RAM modules at 6GB. Newer DDR3 MBs may have a different setup. A 32bit OS can only use a bit less than four GB. A 64bit can use quite a bit more. The specifications you look at are Cas ratings, timings and operating voltage. I've been using OCZ RAM lately and it works fine with my AMD Phenom II 920. But it's DDR2 1200.

[A Traveller]

Hi MOVIEGEEK. Newegg didn't have the motherboard listed in it's configurator. It didn't even have the socket (AM3)! so I chose the nearest one, which supports 1.8V DDR2 DIMMs, according to the specs at it's website. However, the list of memory returned by the configurator included memory that is rated at 2.1v.

Hi redwudz. Even if I don't increase the voltage in BIOS, I am guessing that the memory will not perform at its optimum level if run at a lower voltage than its rated voltage, ie. 1.8v memory in a 1.5v motherboard.

It's ok, I don't plan on getting value RAM. I was thinking of the following.

http://www.gigabyte.com.tw/Products/Motherboard/Products_Overview.aspx?ProductID=3154
http://www.misco.co.uk/applications/searchtools/item-Details.asp?EdpNo=366414&sourceid=2003

Someone at another site suggested that CAS would be affected if the voltage is increased (or maybe even if it's not increased but a higher voltage memory used?). They also said that when they increased the voltage, the memory became warm (or warmer).

There is suitable gskill memory listed in the motherboard's list, but I am worried about compatibility issues with hardware as well as software. Does anyone know of any compatibility problems of gskill memory with hardware? (I'll query compatibility with Linux in the correct board.)

Thanks.

[MEL15]

One question to all of you.Just installed 4 gig of ddr2 ram on my computer.

But only 3 and a 1/4 of ram shows.Is that normal? Tried the same chips on my sons computer,his shows 3 gig.

[redwudz]

One question to all of you.Just installed 4 gig of ddr2 ram on my computer.

But only 3 and a 1/4 of ram shows.Is that normal? Tried the same chips on my sons computer,his shows 3 gig.

Yes, it's normal. With a 32bit OS, the system can only address a bit less than 4GB, usually up to 3.7GB, but it can be less if some RAM is allocated to a video card. This is true with most all 32bit OS's.

[MEL15]

One question to all of you.Just installed 4 gig of ddr2 ram on my computer.

But only 3 and a 1/4 of ram shows.Is that normal? Tried the same chips on my sons computer,his shows 3 gig.

Yes, it's normal. With a 32bit OS, the system can only address a bit less than 4GB, usually up to 3.7GB, but it can be less if some RAM is allocated to a video card. This is true with most all 32bit OS's.

Thanks for the info.

[redwudz]

A Traveller, most newer MBs are a bit more compatible with RAM than ones a few years ago. My Intel Gigabyte MB computer changed my RAM voltage automatically to the correct 2.1VDC, even though the default was 1.8VDC, so I didn't have to adjust it manually. Even though you are in the UK, the NewEgg site is a good place for research as they usually have lots of feedback about RAM compatibility on most of the more popular MBs.

And that's a very popular AMD MB, and from their varied listing of recommended RAM, it doesn't seem to have much in the way of compatibility problems. I would download the MB manual before you order the MB to familiarize yourself with the RAM settings and all. If you are using DDR3, you might have to use three channel RAM, (Three modules) or dual channel (Two modules) may work. The MB manual should tell you that. I use a GA-MA78GPM-UD2H in my HTPC with 4GB OCZ DDR2 PC6400 RAM (1066Mhz) and a Phenom II 920 CPU.

Cas can be affected by voltage, but I doubt if you would notice much difference. A handy utility, CPU-Z will tell you what settings your RAM is running at and if it is running at the optimal settings. http://www.cpuid.com/cpuz.php But I don't think it runs on Linux. Most modern MBs will self configure the RAM you install and you shouldn't have to change anything unless you notice poor performance.

DDR3 is fairly new and the prices are a bit high at present, but dropping. It does perform better than DDR2 RAM.

RAM module selection can be confusing. That's mainly because there are so many suppliers out there. The secret is most use the same RAM chips as there aren't that many RAM chip suppliers. (Micron is one common chip suppler) The only thing different between the RAM module suppliers are how they set up their RAM modules and how they do their testing and quality control. Even a cheap RAM module may use the same exact RAM chip as an expensive module. I stay with the major module suppliers because they honor their guarantees better and their carrier boards are better quality. Having heat spreaders is a big plus with any high performance RAM module as they should run cooler. Kingston and G-Skill seem to be a good companies and I have used their RAM modules with no problems.

[A Traveller]

Thanks redwudz.

You couldn't be more right when you say that "RAM module selection can be confusing"!!!!

It's a long time since I last dealt with memory. It was pc100/133 in those days and and as far as I can remember, the numbers were the same for compatible hardware. However nowadays, as an example, there is pc3 12800 memory but nowhere in the motherboard specification is this number mentioned. The motherboard specs state 5200 MT/s so I am struggling at the moment to tell if a) the memory is compatible with the motherboard, b) if the memory will operate at its max and c) if the motherboards capabilities are fully utilised.

[rcubed]

A Traveller,
Sometimes the RAM will have default settings that are slower than those which can be utilized if the DRAM supply voltage is raised. These setting are usually read from the DRMA chips by the mobo from the SPD settings (i.e. the See the attached data sheet from Corsair as an example). On my Asus Mobo (it uses DDdR2), the default setting for the DRAM shown are the 5-5-5-18 at somewhere around 1.95V. When I adjust the timing to the 4-4-4-12 I have to raise the voltage to 2.1V. The memory might not operate correctly at the higher speed unless the voltage is raised. As was mentioned the down side is higher voltage and higher speed equal more power dissipation. I agree it can get confusing and which parameter is which can also be confusing. Also the chip manufactures can offer guidance about RAM choices.

Good luck with your choice.

BTW how is the choice for Mobo components going.

rcubed

twin2x1024-6400c4.pdf

[usually_quiet]

They always warn you that increasing the RAM voltage may damage it. But if it's rated for that voltage and has a guarantee, not a big problem as you aren't really increasing it, you are putting it at the manufacturer's default RAM voltage. The DDR2 RAM I use in one computer is rated for 2.1VDC and that's what I run it at. The manufacturer garantees it will run at voltages up to 2.5 volts, but I don't need that as my overclock isn't high enough to need a increase in RAM voltage for stability.

If you want performance and stability, I would stay away from 'Value RAM'. Get a good brand, Mushkin, OCZ, Crucial, Corsair, or others with heat spreaders and a lifetime warranty.

What motherboard and CPU are you using? With DDR3, some use a triple channel RAM setup with three RAM modules at 6GB. Newer DDR3 MBs may have a different setup. A 32bit OS can only use a bit less than four GB. A 64bit can use quite a bit more. The specifications you look at are Cas ratings, timings and operating voltage. I've been using OCZ RAM lately and it works fine with my AMD Phenom II 920. But it's DDR2 1200.

The OP appears to need something different, but I bought Kingston Value RAM for myself. While it doesn't have heat spreaders, Kingston Value RAM does have a lifetime guarantee. Performance and stability under intensive use are not something I need to be concerned about, so I didn't need heat spreaders.

[budz]

GSkill is another good ram to purchase.
Just my 2 cents!

[A Traveller]

Ok, thanks for the information.

rcubed, I think I'm getting closer to choosing. I have finally decided on the PSU (see the PSU thread). My choice of motherboard and graphics card have remained unchanged (may go for a different 'edition' card though). I'm still finding the voltage situation to be over my head, but I take it that it doesn't really matter, so I'll just go ahead and purchase RAM that is on the motherboard support list, regardless of what the voltage is.

Audio and ethernet is onboard, so I don't need to purchase them.

So now the only thing I need is a case! I have heard that the GTX 260 is a BIG card, so I need to figure out how to find a case to accommodate this card but also ensure that the PSU cables can reach the drives! From researching the Internet, I a common complaint of this card was that people only barely managed to fit it in their cases.

[A Traveller]

Ok, I've now come across some more annoying information. The specs for the processor I wish to use is as follows.

Integrated DRAM Controller with AMD Memory Optimizer Technology
A high-bandwidth, low-latency integrated memory controller
Supports PC2-8500 (DDR2-1066); PC2-6400 (DDR2-800), PC2-5300 (DDR2-667), PC2-4200 (DDR2-533) or PC2-3200 (DDR2-400) SDRAM unbuffered DIMMs – AM2+
Support for unregistered DIMMs up to PC2 8500(DDR2-1066MHz) and PC3 10600 (DDR3-1333MHz) – AM3
Up to 17.1GB/s memory bandwidth for DDR2 and up to 21GB/s memory bandwidth for DDR3
Benefit: Quick access to system memory for better performance.

Does this mean that with this processor, the memory will only go up to 1333 MHz even if 1600 or 1666 is installed?

Sorry for the further question, but websites seem to have the annoying habit of leaving out important specs and it's only by accident that additional specs are stumbled upon whilst browsing other sites.

Thanks.

[usually_quiet]

The way I read the posted specs. the processor you want only supports DDR2 memory up to 1066 MHz, and DDR3 memory up to 1333 MHz.

Now I'm confused. In another thread you said you were buying a GA-MA785G-UD3H motherboard and a Phenom II CPU. If not, it might be helpful to know what motherboard and CPU you have decided upon. If it is still true, then to use DDR3 memory, you would need a different motherboard. That one only takes DDR2 memory.

[A Traveller]

Hi usually_quiet.

'The way I read the posted specs. the processor you want only supports DDR2 memory up to 1066 MHz, and DDR3 memory up to 1333 MHz.'

That's what I understood it to be also.

Yes, I was planning on buying a GA-MA785G-UD3H motherboard and a Phenom II CPU. This is why I posted back here again, because I was hoping that my understanding of the info provided in the specs would be wrong.

'If it is still true, then to use DDR3 memory, you would need a different motherboard. That one only takes DDR2 memory.'

Don't forget, the specs I listed are from the processor, not the motherboard. The motherboard supports up to 1666 and 1800 if overclocked. The memory I will be buying is 1600.

I could have provided a link to the relevant info, but the AMD site is currently down for routine maintenance.

Thanks.

[redwudz]

The Taiwan site for Gigabyte lists this info for the GA-MA785GT-UD3H Rv 1.0 MB.

Dual Channel DDR3 1800+ for remarkable system performance

DDR3 1600 should work fine. Sometimes they list a odd number for RAM speed and what they may mean is the RAM can be overclocked to that speed, depending on the CPU being used and if the RAM can run that fast. But I would just look for a compatible DDR3 1600 RAM setup. You would want a dual channel set of RAM modules for best performance.

From looking at the MB manual, two RAM modules will work fine. Then you just need a compatible dual channel set of modules.

From NewEgg, these seem to be compatible: http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=2010170147%201052129233%20...ue&Order=PRICE

You could search your UK sources to see if they list these and at what prices. US prices are about $80US on up. If OCZ is available, they seem to work well with AMD chipsets, G-Skill, Mushkin, Corsair, and other major suppliers should all have equivalent dual channel sets.

Good luck.

[usually_quiet]

I got the information for the GA-MA785G-UD3H (Rev 1.0 ) from Gigabytes's US website. It only mentions DDR2. No wonder I'm confused.

http://www.gigabyte.us/Products/Motherboard/Products_Spec.aspx?ClassValue=Motherboard&...GA-MA785G-UD3H

I know that versions sold in the US sometimes differ, but surely not that much. They need to update the US listing.

[A Traveller]

Thanks redwudz/usually_quiet.

I think that you all haven't still quite understood my question. Sorry I haven't explained it totally clearly.

Ok, I had already chosen the motherboard and the memory. There is no problem between these two. I had checked the specs for both and made sure that they were compatible with each other and that the memory could use it's maximum speed. That's about the only thing I DO know how to do! Haha.

The information I provided for the processor (that only up to DDR3 1333MHz) memory is supported was from the actual AMD Phenom II processor, not the AMD chipset on the motherboard or anything else to do with the motherboard.

This AMD site is still down for maintenance, however, I managed to pull up a cached page. Please see the section that is highlighted in yellow. If it isn't, it is about the 'Integrated DRAM Controller'.

http://209.85.229.132/search?q=cache:PP8vM-BZeNoJ:www.amd.com/us/products/desktop/proc...&ct=clnk&gl=uk

I didn't remember this when I originally posted, but this info seems to be for ALL Phenom II processors, not just any particular models. Surely, it can't mean that all Phenom II CPUs can only utilise 1333MHz RAM speed!

Thanks and sorry for the confusion.

[usually_quiet]

I read the specifications as saying you should not use DDR3 memory having a stock speed higher than 1333 MHz with a Phenom II processor.

To find out more, I Googled "phenom II ddr3 memory controller" and found an article on TweakTown dated Mar 11, 2009, on DDR2 and DDR3 memory performance with a Phenom II CPU, using a different motherboard than yours. Just, so anyone who wants to read the article knows, there were numerous pop-ups on that site that, thankfully, FireFox blocked for me.

http://www.tweaktown.com/articles/1782/amd_phenom_ii_ddr2_vs_ddr3_performance/index.html

In that article the testers stated that they used 1066MHz DDR2 and 1333MHz DDR3 memory for testing because those were the maximum stock speeds for memory that AMD supported. In other words AMD does not recommend using memory with higher stock speeds than that, but no doubt people do it anyway, or overclock their memory.

I can only guess, but any DDR3 supported by the motherboard would probably run at its stated stock speed, unless you choose to do something else.

[A Traveller]

Ok, thanks for that usually_quiet. Yes, that is exactly what I was trying to find out. Thanks. I find it extremely strange though. 1600MHz memory is the norm and the latest, highest speed AMD CPU only supports up to 1333MHz! That is beyond stupid! Thanks for all the help and good advice everyone.

[usually_quiet]

It turns out, without realizing it, I am using my Athlon II x 2 250 Regor CPU with DDR3 memory that is above AMD's highest recommended speed for it. For that processor AMD supports up to DDR3 1066 MHz and I have DDR3 1333 MHz installed. The technical information I read before I bought it said nothing about the maximum recommended stock speed for DDR3 memory. I had to make an effort to find it.

The memory is running at 1333 MHz with no problems, as far as I can determine, but nothing I do is likely to put a heavy load on my system.

[rcubed]

Ok, thanks for that usually_quiet. Yes, that is exactly what I was trying to find out. Thanks. I find it extremely strange though. 1600MHz memory is the norm and the latest, highest speed AMD CPU only supports up to 1333MHz! That is beyond stupid! Thanks for all the help and good advice everyone.

A Traveller,

The mobo memory (RAM) will have an effect on the processing speed, but an even bigger effect is how the cache(s) on the CPU chip are organized, and the program being run. Some CPUs have multiple level of caches and how they are allocated to CPUs is especially important on n-way (duals, quads, etc). Things like associativity. That and how the CPU does prefetching of instructions and data. If a program is running a loop and the loop is of a size that can be contained in the cache, then at least for instruction fetching there will be no references to RAM memory. Also the width of the data path between the CPU and RAM will have a large effect on overall speed. That is why redwudz was recommending a matched set of RAM modules and setting the mobo to run in dual channel mode. That way both RAM chips can be accessed in parallel effectively doubling the memory bandwidth with a resulting increase in performance. IMHO AMD always did a pretty good job of balancing the performance of their chips. Faster is usually better, but it does not always equate to higher performance. It gets very complicated and there are a lot of trade offs that have to be considered in the design of the CPU and memory management.

rcubed

[A Traveller]

usually_quiet, your post sums up EXACTLY what I think happens to the majority of 'ordinary' consumers (like myself) buying these computer parts. Up until now, I thought that all that needed to be checked when purchasing memory, was whether or not the motherboard supported it. As you can gather from one of my previous posts, I even thought that the CPU manufacturer may be referring to something else when they had written about supporting only up to 1333. Even IF I had any idea that the CPU also needed to support the RAM, I would have automatically assumed that the new processors of today wouldn't even need checking for compatibility. I would have thought that they would be built to support speeds well beyond the current RAM maximum.

Does ANY CPU support higher speeds that 1333MHZ?

Thanks rcubed.

I contacted AMD directly and they confirmed our deepest, darkest fears! Haha. Basically, they said that only up to 1333MHz is supported, however, higher speed RAM (e.g. 1600MHz) may or may not work. There is no guarantee. I think that it is a similar situation as when motherboards have a list of supported memory. It doesn't necessarily mean that any memory not listed will not work. It just means that the list only consists of memory which they have tested. There are hundreds more which they have not tested, but may work 100% fine. I get the impression from AMD's response that they have only tested up to 1333MHz and so, it is not a case of 1600MHz not working, it is just that they haven't tested it so they cannot say that the CPU 'supports' it.

In light of all of this, I think it may be a wise idea to go for 1333MHz RAM instead of the 1600 I originally planned on getting.

Hope the above helps anyone who is in search of the same issue.

[usually_quiet]

Does ANY CPU support higher speeds that 1333MHZ?

AMD's quad cores don't, and Intel's i7 CPUs don't officially support more than 1333MHz either, so I guess the answer is "No". In fact one of Intel's pages for i7 processors says: "3 Channels of DDR3 1066 MHz memory"

[A Traveller]

Thanks usually_quiet.