Question Max Ram Supported for i7 2600 cpu and 1155 lga motherboard

May 6, 2020
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I purchased a Dell Optiplex 390 computer that came with an i5 processor and one 4GB stick of 10600 1333mhz DDR3 RAM at 1.5v.

I upgraded the CPU to an i7 2600 and it works fine.

The specifications of the instruction manual say the maximum supported RAM is 8GB - which it says is 4GB for each of the two RAM slots. The instruction manual says the maximum supported RAM speed is 1333mhz.

However, I have repeatedly read online and seen on YouTube that the maximum supported RAM is 16GB.

And I have repeatedly read online that the maximum supported RAM is faster than 1333mhz. Multiple sources have said the computer is compatible with 12800 RAM speeds of 1600mhz, and even 15000 RAM speeds of 1800mhz.

I have read that crucial.com is one of the most reliable sources. I used this website to learn some things.

First, I used crucial.com on an HP laptop I have as a test. This HP laptop has instructions that say it has a maximum supported RAM of only 8GB. But, crucial.com shows a maximum supported RAM of 16GB of RAM of up to 1600mhz speed. This confirms exactly what I had read online for that laptop. This told me instructions are not always reliable, and it seemed to confirm crucial.com knows what it is talking about.

I then used crucial.com on the Dell Optiplex 390. I was surprised when crucial.com said the maximum supported RAM is 8GB. The options available for sale were all 4GB sticks of 12800 1600mhz RAM. The option of using a single 8GB stick of RAM was not available.

On the crucial.com website, it specifically shows an asterisk and said:

* Not to exceed manufacturer's supported memory

The instruction manual of the Dell Optiplex 390 points out that RAM is supposed to be 1.5v. However, all of the 4GB RAM sticks that crucial.com recommended were 1.35v. And the fact that the RAM that crucial was recommending was 12800 1600mhz DDR3 RAM is faster than what the instruction manual recommends. This again makes me think that the instruction manual may not always be correct. However, the fact that crucial.com supports the thought that 8GB is the maximum supported RAM makes me think it really is, even though other websites say otherwise.

Does anyone know for sure what the answer is?

I do not want to risk causing my desktop Dell Optiplex 390 mini tower to overheat or suffer a side effect from too much RAM or the wrong kind of RAM.

I know that increasing speed from the 10600 1333mhz RAM to 1600mhz 12800 RAM is not that big of a speed difference. But, I have been told that if I upgraded from the 10600 1333mhz to the 15000 1800mhz Viper 3 RAM, there would be a noticeable difference. Is that correct?

I use a lot of Handbrake for video compression, and I use a lot of Magix video editing software for video encoding. I do not play a lot of games.

I know this Viper 3 15000 1800mhz DDR3 RAM can potentially "overclock" to 1.8v, but I would not do that. I do not do any type of "overclocking" and I don't want "overpowering." That RAM simply caught my eye because it was over 1800mhz, which is obviously quite a bit faster than 1333mhz.

If anyone can tell me what the true limit for RAM is with a Dell Optiplex 390 with an i7 CPU, 2 DDR3 RAM slots, and an LGA 1155 motherboard, I would appreciate it.
 
May 6, 2020
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What is the EXACT motherboard model, as printed directly on the motherboard?
Can you please tell me if the "Exact Motherboard Model" is something that can be obtained from either the CPUID freeware? If so, where?

And can you please tell me if the "Exact Motherboard Model" is something that can be obtained from the crucial.com website? I am referring to the way the crucial.com website refers to the "Chipset" information.

If neither of those offer the information, is there any other way to obtain the information? I am not sure where to look inside the computer if I need to look on the motherboard itself.
 
If anyone can tell me what the true limit for RAM is with a Dell Optiplex 390 with an i7 CPU, 2 DDR3 RAM slots, and an LGA 1155 motherboard, I would appreciate it.
i7 2600 ram limit is 32GB. It can use ram up to 1333mhz. Usage of higher frequency ram requires overclocking. Overclocking capabilities depend on motherboard. Also motherboard determines ram modules, that can be used.

Theoretically you could use 2x8GB DDR3 ram modules with your system. But motherboard is not validated to be used with 8GB ram modules. Might work, might not.

https://ark.intel.com/content/www/us/en/ark/products/52213/intel-core-i7-2600-processor-8m-cache-up-to-3-80-ghz.html
 
May 6, 2020
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i7 2600 ram limit is 32GB. It can use ram up to 1333mhz. Usage of higher frequency ram requires overclocking. Overclocking capabilities depend on motherboard. Also motherboard determines ram modules, that can be used.

Theoretically you could use 2x8GB DDR3 ram modules with your system. But motherboard is not validated to be used with 8GB ram modules. Might work, might not.

https://ark.intel.com/content/www/us/en/ark/products/52213/intel-core-i7-2600-processor-8m-cache-up-to-3-80-ghz.html
Based on what I have read online, the i7 2600 CPU is not capable of "overclocking." It is the i7 2600k CPU processor that is capable of "overclocking." Is this correct?"

The information you provided states that the i7 2600 CPU has a limit of 32GB of RAM, with two RAM slots used. This means it would be compatible with two 16GB RAM sticks of 1333mhz speed. Is that correct?

If that is correct, why do the instructions and the crucial.com website make such a fuss about using anything more than 4GB in the RAM slot?
 
Based on what I have read online, the i7 2600 CPU is not capable of "overclocking."
Was talking about ram overclocking here. CPU overclocking is not the same as ram overclocking.
The information you provided states that the i7 2600 CPU has a limit of 32GB of RAM, with two RAM slots used. This means it would be compatible with two 16GB RAM sticks of 1333mhz speed. Is that correct?
No. Not correct.
With 2 slots, you're limited to 16GB total. 2x8GB DDR3 ram modules. But such config is not validated. Still - should be possible.
If that is correct, why do the instructions and the crucial.com website make such a fuss about using anything more than 4GB in the RAM slot?
Because motherboard is not validated for such config.
 
May 6, 2020
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What is the EXACT motherboard model, as printed directly on the motherboard?
I used the CPUID CPU-Z freeware program to tell me the information about "the exact motherboard model."

Here is the information provided on the tab labeled as "Mainboard."

Motherboard

Model: 0M5DCD A00
Chipset: Intel Sandy Bridge Rev. 09
Southbridge: Intel H61 Rev. B2
 
May 6, 2020
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i7 2600 ram limit is 32GB. It can use ram up to 1333mhz. Usage of higher frequency ram requires overclocking. Overclocking capabilities depend on motherboard. Also motherboard determines ram modules, that can be used.

Theoretically you could use 2x8GB DDR3 ram modules with your system. But motherboard is not validated to be used with 8GB ram modules. Might work, might not.

https://ark.intel.com/content/www/us/en/ark/products/52213/intel-core-i7-2600-processor-8m-cache-up-to-3-80-ghz.html

You said, "It can use ram up to 1333mhz."

You also said, "Usage of higher frequency RAM requires overclocking."

The crucial.com website lists only 1600mhz 4GB RAM modules. Does this mean "overclocking" of the RAM would be required in order to use this frequency of 1600mhz with the 4GB RAM modules?

Or, would the computer simply operate at the speed of 1333mhz rather than 1600mhz if nothing was done to adjust "overclocking"?

I'm asking because those Viper III RAM sticks that are 15000 1800mhz actually cost less than the 12800 1333mhz DDR3 RAM. So, as long as there was no technical "risk" of overheating the motherboard or being incompatible with the CPU or overheating the CPU, it would seem to make sense to buy the faster RAM that costs less.

What are your thoughts?
 
The crucial.com website lists only 1600mhz 4GB RAM modules. Does this mean "overclocking" of the RAM would be required in order to use this frequency of 1600mhz with the 4GB RAM modules?

Or, would the computer simply operate at the speed of 1333mhz rather than 1600mhz if nothing was done to adjust "overclocking"?
H61 chipset doesn't allow overclocking.
With i7-2600 you're limited to 1333mhz ram operating mode. Higher frequency ram will be down-clocked to 1333mhz.
 
May 6, 2020
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H61 chipset doesn't allow overclocking.
With i7-2600 you're limited to 1333mhz ram operating mode. Higher frequency ram will be down-clocked to 1333mhz.
Thank you very much for your help.

Now, I'm just wondering if it makes more sense to buy a RAM stick that uses 1.5v as the instruction manual suggest? Or 1.35v as the crucial.com website suggests?

The RAM currently used is 1.5v. So, I know it is compatible. In theory, would it make more sense to use the RAM with less power, because it generates less heat? Or is there any time when less power means worse performance?

By the way, how did you obtain so much information about these things such as motherboards, RAM, and CPUs? The way you knew the H61 chipset is not compatible with overclocking is very impressive.
 
1.35V DDR3 is called DDR3L.
It started appearing with 6th gen intel core cpus. Somewhere ~ year 2015.
At the time of i7-2600 it was not available. So there might be compatibility issues.

Info about different chipsets/motherboards you can find on internet. For example - try google search on some manufacturer H61 board like "MSI H61" or "Asrock H61". All the compatibility info on those will be identical.

You can also find info on Intel cpus and chipsets at ark.intel.com
 
May 6, 2020
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1.35V DDR3 is called DDR3L.
It started appearing with 6th gen intel core cpus. Somewhere ~ year 2015.
At the time of i7-2600 it was not available. So there might be compatibility issues.
I had originally seen a video on YouTube saying that Laptop SODIMM DDR3L 1.35V RAM could be used on Desktops with an adapter. This was confirmed in multiple videos. You could even use more than one stick of RAM, as long as both of them were SODIMM DDR3L 1.35V RAM sticks.

The Laptop SODIMM DDR3L RAM could also be used with a Desktop if the Laptop RAM was the older 1.5v.

I think it must be safe to presume that the Desktop DDR3 RAM that is 1.35v is compatible with the i7 2600 CPU and LGA 1155 Motherboard, along with this H61 chipset. My basis for saying that is because crucial.com only listed RAM sticks that were 1.35v.

Is that something you would agree with? Does crucial.com get things wrong sometimes?
 
I think it must be safe to presume that the Desktop DDR3 RAM that is 1.35v is compatible with the i7 2600 CPU and LGA 1155 Motherboard, along with this H61 chipset.
Motherboard compatibility specification don't list DDR3L as compatible.
Should work - yes, probably will work at 1.5V. But issues are possible. You'll know, when you try it.
DDR3 1.5v is compatible for sure.
 

Darkbreeze

Titan
Moderator
H61 can support up to 1600mhz memory if the BIOS supports it. Plenty of H61 motherboards using 1600mhz memory. It's the CPU that's the limitation.

I would avoid the DDR3L modules and stick to DDR3 memory kits that are intended for 1.5v operation.
 
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Darkbreeze

Titan
Moderator
Right, with 2nd Gen on locked chipset you'll be limited to 1333mhz, but you CAN still use the 1600mhz sticks if they are cheaper or are all you can find, and just run them at 1333mhz. Probably run better anyhow since they'll be running well below what they could be run at.
 

Darkbreeze

Titan
Moderator
There are MANY motherboards that are not designed to deal with low voltage requirements from DDR3L memory. You CAN however run all DDR3L memory modules at 1.5v, and then they will work fine. DDR3L memory is exactly the same as DDR3 memory, but is simply higher quality "binned" samples that are able to work properly at lower voltages due to being extremely well binned.

So in that regard, you are right. As far as all H61 and other older chipsets being capable of "working fine" with 1.35v memory, simply not true. There are a lot of boards out there, especially OEM boards that are typically equipped with ONLY the basics necessary to support the hardware it is intended to support, unlike aftermarket boards that are intended to support a WIDE variety of hardware, that will not support 1.35v sticks. And in some cases they will support it just fine.

The reason I say to avoid the DDR3L modules is because users will likely need to manually configure the memory voltage settings rather than them being defaulted to an appropriate voltage and that may not be assumed to be a no brainer for all users that come through here or any given user in general.
 

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