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Installing DDR3 memory on Corei5 2500k

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February 16, 2011 11:08:00 PM

When having 4 memory slots on a core i5 mobo, does it matter which ones I use to install 2 memory modules in?

I can either use the same memory bank (slot 1 and 2) or should I use the different banks for increased performance (slot 1 and 3 or 1 and 4)?

What would be best for best performance?
What would be best for lowest power consumption?
What would be best when overclocking? (not that I do such a thing, but it might be an interesting question for others).
a b } Memory
February 17, 2011 2:33:24 AM

If you are only using two of the slots, the memory should be in the second and the fourth (starting from the CPU). That makes for one stick in each channel. The first and third slot should only be used if you are installing four sticks of RAM.

If you put the RAM in the wrong slots, the computer likely won't boot up. That takes care of all of your questions.
a b } Memory
February 17, 2011 2:44:55 AM

You should use the same-colored memory slot; 1 & 3 or 2 & 4. Doing so will make your system utilize dual-channel mode, which gives ~10% performance boost.

If you put it in not-same-colored way; 1 & 4 or 2 & 3, your system will not utilize dual-channel mode, running at single-channel. Therefore it's ~10% performance loss than dual-channel mode.

For best performance, use 2 DIMMs of 2Gb (4Gb total) is better than using 16 GB of 4 DIMMs of 4 Gb.
http://www.bit-tech.net/hardware/memory/2011/01/11/the-...

All memory use same power consumption, so it's a standard rather than "which-one-is-less-power-consuming". All memory DDR3 is capped at max 1.65V by JEDEC standard. Of course, you can tweak through BIOS setting, if you have time, to have less power.

Best memory for overclocking?
Well, that depends. If you're heavy overclocker that overclock to, say, 4.5 Ghz, then 1866/2000 is your choice. Most users us gamers and little overclocking, use 1600 Mhz.
Related resources
a b } Memory
February 17, 2011 3:27:59 AM

Benchmarks don't tell the whole story though. I have a 4GB kit and an 8GB kit in my Sandy Bridge machine. I have tried both of them separately, and I could immediately tell which one was in the machine based on overall feel.

More memory allows games to load quicker, levels/maps load quicker, some games will allow you to select more detailed graphical options. Plus, multitasking is handled better. The overall experience is smoother. Benchmarks don't show that.

Read this page. To see those same screens on your computer, go to the Windows Experience Index page and click the "View and print detailed performance and system information" link on the right side.

The more system RAM you have, the more your video card can use during demanding games. That results in smoother gaming.
a b } Memory
February 17, 2011 6:22:19 AM

There's a difference between system memory and GPU memory. The graphic processing takes place in GPU memory, not system memory. The GPU memory is dedicated, so it's separated from your system's memory. No matter how many system memory you have, it won't affect the performance of your GPU, nor the GPU will take it for graphic processing, because the GPU uses its own separate GPU memory (ex. 8800GT 512MB). But sometimes there are some cases that system's memory is shared with graphic card's memory usage. I dunno why it happens, though..

It's true that more RAM gives more breathing room, but too much RAM is wasted. The key is to know, how much will the games need. How to know that is by looking at game's system requirements. Games now still only require 4GB (recommended) memory in their syst. spec. So having more RAM is a waste, unless you run 3 or 4 games at the same time.
a b } Memory
February 17, 2011 6:43:00 AM

Graphics cards have long had the ability to use system RAM for texture storage and such (since AGP days). Modern games are finally to the point of actually needing the graphics card to use that ability. Future games will use it even more.

My GTX 570 has 1280MB of its own. It still reserves 2815MB of system RAM for that texture storage, for a total of 4095MB of graphics memory.

If I didn't have more than 4GB of system RAM, it wouldn't be able to reserve as much memory, and games wouldn't be as smooth because of this. I have tested it on my system, and verified that it's the truth -- games don't feel as snappy with less than 8GB of RAM.

6GB is the absolute minimum I would recommend to a gamer. Because this is a weird number and requires two kits (one 2x2GB kit and one 2x1GB kit) for dual-channel mainboards, it's just easier to recommend 8GB.
a b } Memory
February 17, 2011 7:14:21 AM

ProDigit10 said:
When having 4 memory slots on a core i5 mobo, does it matter which ones I use to install 2 memory modules in?

I can either use the same memory bank (slot 1 and 2) or should I use the different banks for increased performance (slot 1 and 3 or 1 and 4)?

What would be best for best performance?
What would be best for lowest power consumption?
What would be best when overclocking? (not that I do such a thing, but it might be an interesting question for others).
Follow the advice first response to assure best stability.
February 17, 2011 1:18:44 PM

Thank you for your replies!

Just to get it straight,
It is better to click the memory in slot 1 and 3 (or 2 and 4) than in slot 1 and 2 (or 3 and 4)

I see many people miss out on that, they generally plug RAM in slot 1 and 2, and experience reduced performance that way!

Is there anything concerning power consumption that can be said when plugging RAM in 1 and 2 vs 1 and 3?

Also, at the moment, I am not running a graphics card. Reason being my wife likes to edit movies, and I am planning on using the Intel IGP.

How is the igp of the core i5 2500k performing on 2 vs 4 RAM modules (meaning, 4x2GB vs 2x4GB)?

I know the sweet spot would be 6GB of system memory for me, but since the Corei5 2500k only supports dual channel DDR3 memory, I guess I'll either go with 2x4GB or 4x2GB.
a b } Memory
February 17, 2011 5:05:58 PM

Yes, slots 2 and 4 should be used first with Sandy Bridge CPUs. The mainboard may not boot up with another arrangement (1 and 3 or 1 and 4). You could try it, but there's no point -- just use 2 and 4 with two sticks of RAM.

Other CPUs may like the RAM to be in slots 1 and 2 instead.

Any differences in power consumption for the various slots would be so small as to make no difference at all. You're getting one of the most power-efficient mainstream CPUs ever created -- you don't need to be worried about the RAM's power consumption.

As far as I know, no one has done comparisons of two RAM sticks versus four RAM sticks with the graphics core enabled. I wouldn't think it matters.

And you can get 6GB dual channel -- buy one 2x2GB kit and one 2x1GB kit. Just make sure they're the same type, speed, and timings. I have 12GB in my machine (one 2x4GB kit and one 2x2GB kit), so I know that odd amounts work just fine.

If you wanted to go with 6GB route, I recommend these two kits:
G.Skill F3-12800CL9D-4GBNQ
G.Skill F3-12800CL9D-2GBNQ
Put the 2GB sticks in slots 2 and 4, and the 1GB sticks in slots 1 and 3, and you're good to go.

For 8GB, go with this one:
G.Skill F3-12800CL9D-8GBXL
Slots 2 and 4 for this kit.
a b } Memory
February 17, 2011 8:18:55 PM

ProDigit10 said:
Thank you for your replies!

Just to get it straight,
It is better to click the memory in slot 1 and 3 (or 2 and 4) than in slot 1 and 2 (or 3 and 4)

I see many people miss out on that, they generally plug RAM in slot 1 and 2, and experience reduced performance that way!

Is there anything concerning power consumption that can be said when plugging RAM in 1 and 2 vs 1 and 3?

Also, at the moment, I am not running a graphics card. Reason being my wife likes to edit movies, and I am planning on using the Intel IGP.

How is the igp of the core i5 2500k performing on 2 vs 4 RAM modules (meaning, 4x2GB vs 2x4GB)?

I know the sweet spot would be 6GB of system memory for me, but since the Corei5 2500k only supports dual channel DDR3 memory, I guess I'll either go with 2x4GB or 4x2GB.
THE MOST COMMON REASON PEOPLE RETURN MOTHERBOARD AS NON-FUNCTIONAL IS THAT THEY USED THE WRONG MEMORY SLOTS AND ASSUMED THE BOARD WAS BAD. It's not just a performance issue, the chipset relies on the memory's built-in termination with the last slot of each bank filled first.
February 18, 2011 5:40:14 PM

Thank you, also about mentioning about equipping the last memory slot.
If the mobo would not work, and the bios beeps turn out it's a memory issue, my standard response would be equipping it with 1 module and testing which slot works; but I guess not all know how to deal with mobo error codes.

For now I'll go with 2x4GB, as it is cheaper than 4x2GB; and I can always expand that way in the future should it need be.

Is it true that equipping only 2 slots result in the memory operating at 1333Mhz, while equipping 4 slots the memory operates at a lower frequency(1066Mhz), or am I misunderstanding this?
a b } Memory
February 18, 2011 9:13:09 PM

ProDigit10 said:
Thank you, also about mentioning about equipping the last memory slot.
If the mobo would not work, and the bios beeps turn out it's a memory issue, my standard response would be equipping it with 1 module and testing which slot works; but I guess not all know how to deal with mobo error codes.

For now I'll go with 2x4GB, as it is cheaper than 4x2GB; and I can always expand that way in the future should it need be.

Is it true that equipping only 2 slots result in the memory operating at 1333Mhz, while equipping 4 slots the memory operates at a lower frequency(1066Mhz), or am I misunderstanding this?
You can still adjust the memory in BIOS, even with four modules.

The memory goes into the second slot first if you only have one module: 0X00. That's because you're "terminating" the end of the first channel with that module. The second module goes in the fourth slot 0X0X if you want "good performance" dual-channel mode but could also work in the first slot XX00 with single-channel mode.
February 18, 2011 9:59:21 PM

Hello there!

I know it is not my topic, but it seem pointless to start one for a small question I have.

I just bought 4gb 1333mhz stick and wondering which slot should I put it in. Later on I am for sure going to purchase second stick and use 2 and 4 slots. But for now with one stick what is my options and differences.
a b } Memory
February 19, 2011 12:06:37 AM

ProDigit10 said:
Is it true that equipping only 2 slots result in the memory operating at 1333Mhz, while equipping 4 slots the memory operates at a lower frequency(1066Mhz), or am I misunderstanding this?

That was true with certain previous processors, but that was a while ago. Sandy Bridge has no such limitation, and can operate even at 2133MHz with all four slots filled. Mine is running at its rated 1600 speed with all slots populated.

dimamu15:
From what I recall, if you only have one RAM stick it should go in slot 2. If that doesn't work, try slot 1.
a b } Memory
February 21, 2011 3:00:10 AM

Leap, is plugging memory in slot 2 & 4 is better than in 1 & 3?
a b } Memory
February 21, 2011 3:24:28 AM

This is the way two sticks should be installed (in a Sandy Bridge system):

Slot 1 (closest to CPU): empty
Slot 2: RAM stick
Slot 3: empty
Slot 4: RAM stick

Most boards simply won't boot up if you have the RAM in the wrong slots. Slots 1 and 3 should only be used if you have four RAM sticks.

Note that this is only for Sandy Bridge systems. Other CPUs may want the memory in slots 1 and 2 or 1 and 3 instead.
a b } Memory
February 21, 2011 5:41:14 AM

Leaps-from-Shadows said:
This is the way two sticks should be installed (in a Sandy Bridge system):

Slot 1 (closest to CPU): empty
Slot 2: RAM stick
Slot 3: empty
Slot 4: RAM stick

Most boards simply won't boot up if you have the RAM in the wrong slots. Slots 1 and 3 should only be used if you have four RAM sticks.

Note that this is only for Sandy Bridge systems. Other CPUs may want the memory in slots 1 and 2 or 1 and 3 instead.


All "Core-i" systems including LGA-1155, 1156, and 1366 need the last slot of each bank filled first.

After that you can do pretty much whatever you want. You can do 1 and 2 for example, but that would be single-channel (note that 2 is filled first). You can do 2 and 4 for dual channel. You can do 1, 2, and 4 for single channel. You can do 1, 2, 3, and 4 for dual channel. You just have to make sure that the last slot of each bank is filled first and that the banks are filled in-order :) 

Practically, I think I covered all the bases on this one.
a b } Memory
February 22, 2011 8:21:01 AM

Crashman said:
All "Core-i" systems including LGA-1155, 1156, and 1366 need the last slot of each bank filled first.

After that you can do pretty much whatever you want. You can do 1 and 2 for example, but that would be single-channel (note that 2 is filled first). You can do 2 and 4 for dual channel. You can do 1, 2, and 4 for single channel. You can do 1, 2, 3, and 4 for dual channel. You just have to make sure that the last slot of each bank is filled first and that the banks are filled in-order :) 

Practically, I think I covered all the bases on this one.

So, 'Last slot in each bank' you mean the 'last' one is the 4th slot? If so, then I understand Leap saying 2 & 4 instead of 1 & 3,
or do you mean that I can go 1 & 3 with slot 3 (last slot) plugged in first then the 1st?
a b } Memory
February 22, 2011 3:43:39 PM

andrern2000 said:
So, 'Last slot in each bank' you mean the 'last' one is the 4th slot? If so, then I understand Leap saying 2 & 4 instead of 1 & 3,
or do you mean that I can go 1 & 3 with slot 3 (last slot) plugged in first then the 1st?
I mean the last slot of each channel. Really, if you want to build Core-i systems without asking over and over you should probably know, 1155 and 1156 have 2 channels, 1366 has three, and 2011 will have four. When we finally get those 2011 motherboards the "correct order" will be:

2
2-4
2-4-6
2-4-6-8

For 1, 2, 3, and 4 modules. Of course, SOME boards will only HAVE four slots, so that order would be 1, 1-2, 1-2-3, and 1-2-3-4. The reason of course is that boards that only have one slot per channel only have the "last" slot per channel.

You fill the channels in order. You fill the last slot of that channel first. Channel 1 is slots 1 and 2 so you fill slot 2, channel 2 is slots 3 and 4 so you fill slot 4, etc.

And it gets worse, many manufacturers start counting from 0, and some even number the slots in the order to be filled rather than the order from the CPU. IT'S ALL SEMANTICS.

I'm trying to get you AWAY from the semantics and tell you to fill the LAST slot of each channel first, comprende?
a b } Memory
February 22, 2011 3:43:51 PM

Just ignore what the manufacturer calls the slots.

Slot 1 is the first slot in channel 1. (this is the slot closest to the CPU)
Slot 2 is the last slot in channel 1.
Slot 3 is the first slot in channel 2.
Slot 4 is the last slot in channel 2.

You want memory in the last slot of each channel first (slots 2 and 4).

If you put memory in the first slot of each channel without having memory in the last slot of each channel, it won't work correctly.

Just do what I've been saying all along, and put two sticks of memory in slots 2 and 4. Only use slots 1 and 3 if you have four RAM sticks.
a b } Memory
February 22, 2011 3:58:01 PM

Leaps-from-Shadows said:
Just ignore what the manufacturer calls the slots.

Slot 1 is the first slot in channel 1. (this is the slot closest to the CPU)
Slot 2 is the last slot in channel 1.
Slot 3 is the first slot in channel 2.
Slot 4 is the last slot in channel 2.

You want memory in the last slot of each channel first (slots 2 and 4).

If you put memory in the first slot of each channel without having memory in the last slot of each channel, it won't work correctly.

Just do what I've been saying all along, and put two sticks of memory in slots 2 and 4. Only use slots 1 and 3 if you have four RAM sticks.


Thanks for the simplification Leaps. For everyone who doesn't understand that simplicity, if X is filled and O is open,

o-x-o-o will work but only in single-channel
x-x-o-o will work but only in single-channel
o-x-o-x works in dual channel
x-x-o-x works in single-channel
x-x-x-x works in dual-channel

Rinse and repeat for 6 slot and 8 slot boards. As for 3-slot triple-channel and upcoming 4-slot quad-channel boards, the last slot of each channel is the only one present...
February 22, 2011 7:46:49 PM

As someone planning a build atm, TYVM for making it as clear as possible, in as many different ways as possible!
a b } Memory
February 23, 2011 5:01:50 AM

I dunno what's happening dude,.. But my knowledge is that if the motherboard has two pairs of differently colored DIMM sockets (the colors indicate which bank they belong to, bank 0 or bank 1) then one can place a matched pair of memory modules. The memory modules are installed into matching banks, which are usually color coded on the motherboard.
That's all I know.
a b } Memory
February 23, 2011 5:10:34 AM

Thank you for the info, Crashman. So now I get it that 1 & 3 cannot work without 2 & 4 put in first due to last slot in channel not filled right. Maybe I can test that before adding it to my knowledge. Thanks alot for your replies btw.
a b } Memory
February 23, 2011 6:17:03 AM

andrern2000 said:
Thank you for the info, Crashman. So now I get it that 1 & 3 cannot work without 2 & 4 put in first due to last slot in channel not filled right. Maybe I can test that before adding it to my knowledge. Thanks alot for your replies btw.
You can test it: It's kind of like using SCSI without the end of the cable terminated, sometimes it works sometimes it doesn't and sometimes it looks like it works whilst your data is being corrupted :) 
February 23, 2011 3:55:39 PM

Alright, I kind of understood how to install the RAM's but thanks for further explaining.
If I may add some fuel to the fire, and get the topic a little deeper,
Imagine if I have 2 x 4 GB of DDR3 1666 Mhz, and 1 stick of 4GB 1033Mhz, how would you set it up?

1666Mhz in 2 and 4,
1033 in 1 or 3?

Or would the system work better when placing both 1666Mhz in one channel (eg: 1 and 2), and placing the 'incompatible' or 'different speed' ram in the second channel?

What would total ram speed be?
a b } Memory
February 23, 2011 6:40:30 PM

ProDigit10 said:
Alright, I kind of understood how to install the RAM's but thanks for further explaining.
If I may add some fuel to the fire, and get the topic a little deeper,
Imagine if I have 2 x 4 GB of DDR3 1666 Mhz, and 1 stick of 4GB 1033Mhz, how would you set it up?

1666Mhz in 2 and 4,
1033 in 1 or 3?

Or would the system work better when placing both 1666Mhz in one channel (eg: 1 and 2), and placing the 'incompatible' or 'different speed' ram in the second channel?

What would total ram speed be?


Hadn't thought about it much. I'd try 1066 in 2-4 and 1600 in 1-3 first and see if BIOS detects it at the slower spec, then try the reverse if it doesn't.

The funny thing is I've tried mixed RAM on 1156 boards and simply can't remember the order I ended up using.
a b } Memory
February 24, 2011 2:41:52 AM

I would try the matching RAM in slots 2 and 4, and throw the other in slot 1.

RAM speed and timings would have to match the crap stick.

To be honest with you, because I'm obsessive about such things, I would toss the crap stick and just use the two matching sticks. There's no way I would need the extra RAM enough to slow down the good sticks.
February 25, 2011 6:31:28 PM

my presumption is if you'd mix a channel with slower ram, the whole channel will work at the slower speed. In this case it might be better to plug the fast ram in 3 and 4, and the slow ram in 1 or 2.

That way at least 1 channel is working at the full 1666mhz; haven't tested it yet though.

I'm still waiting for the newer mobo's that support the sata 3 ports, as well as for a newer sata6 ssd to come public.

If all goes well I'll be able to replace my c2duo system soon(~beginning to mid march), which hopefully will serve me for another 5 to 6 years!
a b } Memory
March 4, 2011 1:06:18 AM

Leaps-from-Shadows said:
Just ignore what the manufacturer calls the slots.

Slot 1 is the first slot in channel 1. (this is the slot closest to the CPU)
Slot 2 is the last slot in channel 1.
Slot 3 is the first slot in channel 2.
Slot 4 is the last slot in channel 2.

You want memory in the last slot of each channel first (slots 2 and 4).

If you put memory in the first slot of each channel without having memory in the last slot of each channel, it won't work correctly.

Just do what I've been saying all along, and put two sticks of memory in slots 2 and 4. Only use slots 1 and 3 if you have four RAM sticks.

From:
http://en.kioskea.net/faq/993-memory-how-to-make-use-du...
Dual Channel: [A1-A2] and/or [B1-B2]

* A1 = 1st place (slot 1)
* B1 = 2nd place (slot 2)
* A2 = 3rd place (slot 3)
* B2 = 4th place (slot 4)
* *[A1-B1] = Group 1 on the motherboard.
* *[A2-B2] = Group 2 on the motherboard.

Seems like a contradiction here.. :pt1cable: 
a b } Memory
March 4, 2011 1:28:42 AM

andrern2000 said:
From:
http://en.kioskea.net/faq/993-memory-how-to-make-use-du...
Dual Channel: [A1-A2] and/or [B1-B2]

* A1 = 1st place (slot 1)
* B1 = 2nd place (slot 2)
* A2 = 3rd place (slot 3)
* B2 = 4th place (slot 4)
* *[A1-B1] = Group 1 on the motherboard.
* *[A2-B2] = Group 2 on the motherboard.

Seems like a contradiction here.. :pt1cable: 


So tell them. Really, nobody in this LGA 1155/1156/1366 thread is responsible for an article that refers to LGA 775 motherboards.

Core "i" (i3/i5/i7) does things one way while "everything else" does it another. This has already been mentioned a few times in this thread, so is this your attempt to point out trouble with another site, or are you simply trying to start trouble at this site?
a b } Memory
March 4, 2011 2:40:05 AM

LOL
ROFL
LMAO

Do you realize how old that article is? Under "Important Notes" those memory speeds are referring to DDR memory. Not DDR2 or DDR3, but original DDR. The chipsets in that day did indeed need the memory in the first slot of each channel.

Somebody updated that out-of-date article with a mention of DDR2 in April 2010, but the rest is many years old.
a b } Memory
March 4, 2011 3:24:45 AM

Leaps-from-Shadows said:
LOL
ROFL
LMAO

Do you realize how old that article is? Under "Important Notes" those memory speeds are referring to DDR memory. Not DDR2 or DDR3, but original DDR. The chipsets in that day did indeed need the memory in the first slot of each channel.

Somebody updated that out-of-date article with a mention of DDR2 in April 2010, but the rest is many years old.
I noticed that too and figured it was talking about VIA's illegal Pentium 4 chipsets, which were LGA-775. Not to mention that DDR1 didn't have on-chip termination while DDR3 does...but that of course doesn't explain the module order of DDR3 LGA-775 boards, which probably ignored the on-chip termination and used motherboard termination instead.
October 20, 2011 9:27:56 PM

Hi. I came across this thread while looking for answers. The OP touched on this but I am still trying to find this out:

What are the pros and cons of doing 2x4GB vs. 4x2GB, other than cost? I also want to get 8GB of RAM, also for a 2500k. I want to know how whether there's any performance difference in each configuration.

Secondly, if Ivy Bridge will have quad channel memory, does that mean IB will for sure perform better with 4 modules in the above choice? I'm just thinking that maybe if there is no difference currently, going the 4x2gb route now would reap benefits later if I do an IB build and reuse the RAM?

Thanks!

May 15, 2012 4:10:22 AM

4 slots are marginally faster, consume lots more power.
2-3 slots are possible, consume less power and work pretty fast too.

Remember, having too much ram available will slow down your computer speed.
It's always better to have the amount of memory installed what you most likely will need in every day life, and 25% more.

I browse, do some word documents, bittorrent and anti virus. I never get over 1,2GB of memory used.
I installed 2GB. On my core I5 I installed 2x4 GB because it uses win 7 64 bit. I seldomly get more than 3,6GB of memory used there, but I thought it was better to install 2xsame memory than 1x4GB and 1x2GB.
!