Which RAM slot to use for an additional stick

Question

I've been reading all around and still don't have clarity as to how to configure my RAM sticks in their slots. My confusion is because posters don't distinguish how the RAM slots are ordered/numbered.

I have the Dell Optiplex 7010, with the Intel i5, 3550, 3.3Ghz processor, with 4GB RAM (in the slot that is numbered #2 on my MOBO, which happens to be the fourth slot, the one furthest to the right of the four slots of the two pairs).

I just bought another 4GB stick of RAM (1600Hz, one that matches the first stick) and want to install it in one of the three remaining slots.

What's confusing about what I read is that my slots are actually numbered, visibly, from left to right as 3-1-4-2, which is not in the order of their positions (1, 2, 3, 4 from left to right). The original RAM stick is in slot #2, "position 4".

My question is, should my new stick (the second stick) go into slot #4 or #1 (as numbered, not as positioned) so as to have dual channel functionality (which I've heard is some 10% faster than single channel)?

I've read that the two sticks should be in the first slot of each pair (e.g., slots numbered 1 and 2 or 3 and 4), as opposed to beside each other (e.g., slots numbered 3 and 1 or 4 and 2). Dell told me to put them beside each other, both in just one pair of slots (e.g., #2 and #4). But what I've read is that they should be "separated", putting each in the first slot of each pair of slots.

What's the best configuration for speed? Should they be beside each other in the same pair of slots, or each stick in the fist slot of each pair of slots. And thanks for clarifying this! Oh, and if each should be in the first slot of each pair, should that be slots 2 and 1, or, 4 and 3? Or does it matter? Thx. And sorry for the overkill descriptions, just trying to be clear about these distinctions.

DELL-Jesse L · Answer

larks2020,

Below is probably more information you need, but thought you may want to scan over it as well.

Memory

The Optiplex 7010 system supports up to 16 gb of memory in the mini-tower (MT), desktop (DT), small form factor (SFF) and ultra-small form factor (USFF) chassis with 64-bit operating system. the memory speed supported is 1333/1600mhz ddr3 memory.

NOTE:
however, when system is installed with Intel® core™ g630, 2.70ghz, 3m, Vt-x, 65w processor, the maximum supported memory speed is 1066mhz regardless of whether the 1333/1600mhz ram is plugged in.

32-bit operating systems can only use maximum 4gb memory address space. certain components within the computer require address space in the 4gb range, any address space reserved for these components cannot be used by computer memory the amount of memory available to the operating system is less than 4gb.

NOTE:
memory modules should be installed in pairs of matched memory size, speed, and technology. if the memory modules are not installed in matched pairs, the computer will continue to operate, but with a slight reduction in performance.

NOTE:
the total amount of available memory will be less than 4gb. the amount less depends on the actual system configuration. to fully utilize 4gb or more of memory requires a 64-bit enabled processor and 64-bit operating system.

what is ddr3 memory?

ddr3 continues the evolution in memory technology and provides several improvements to the existing ddr2 architecture. the primary benefit is an increase of the i/o bus to operate at 4 times the speed of the memory cell it contains. ddr3 also allows for chip capacities from 512 mb to 8 gb. this ability in effect allows for memory modules of up to 16 gb in size.

CAUTION:
memory slots on system boards that support ddr3 are keyed to onlY accept ddr3 modules. ddr2 will not fit into a ddr3 slot and ddr3 will not fit into a ddr2 slot.

memory configuration

DDR memory can run in dual-channel mode, which allows the system to have twice the memory bandwidth using the same memory technology.

dual-channel configurations

to achieve dual-channel performance, the total memory in each channel must be the same. if the channels do not match or if the system has only one dimm installed, the system memory operates in single-channel mode or in dual channel asymmetrical mode. the system works normally in single-channel mode, but the user loses the benefit of increased memory throughput.

dual-channel mode is always present when both memory channels are populated. however, for optimum dual-channel performance, the size of the modules must match.

memory channels
channel a	channel b	BIOS says	performance
dimm	no dimm	single channel	single channel
dimm	same as channel a	dual channel interleaved	dual channel interleaved
dimm	same as channel a except speed	dual channel interleaved (in lowest dimm speed)	dual channel interleaved (in lowest dimm speed)
dimm	same as channel a except density	dual channel interleaved	dual channel interleaved
dimm	same as channel a except size	dual channel asymmetric	single channel
no dimm	dimm	single channel	single channel

basically, when both dimm connectors are populated, the system has optimum dual-channel performance unless channels a and b have different amounts of memory.

memory speeds

some confusion has been created due to the difference in the actual listings for speed ("mhz") and the way memory is described from a sales standpoint ("pc XXXXXX"). the listings below should resolve any confusion.

NOTE:

1600mhz memory will only perform as 1600mhz memory when 3rd generation (iVb) cpus are used. it will perform as 1333mhz memory if 2nd generation (snb) i3 2130, i3 2125, i3 2120, g860, g850 cpus are installed in the system. it will perform as 1066mhz memory if 2nd generation (snb) g640, g630, g540, g530, g460 cpus are installed in the system.

Type	DDR3 synch dram non-ecc memory
Memory speed	1333/1600mhz
Memory connectors	four (MT, DT, SFF), two (USFF)
Memory capacities	2gb, 4gb, 6gb and 8gb
Minimum memory	2gb
Maximum memory	32gb on MT, DT, SFF 16gb on USFF

pc3-6400 = 800 mhz

pc3-8500 = 1066 mhz

pc3-10666 = 1333 mhz

pc3-12800 = 1600 MHz

For me to better assist in troubleshooting, please click my DELL-Jesse L and send me a Private Message with the Dell Service Tag number and your Dell Order number.

larks2020 · Answer

Hi Jesse-

Thanks for taking the time to respond. You provided lots of info, most of the relevant items I already knew regarding buying a second RAM stick (e.g., sticks should be same GB, same MHz, etc.). But, unfortunately, you didn't actually answer my question: WHICH slot does the additional stick go into (see my prior post about specifics re slot order and numbering)?

To respond to your points, both sticks are identical in capacities, 4GB, 1600 MHz, DDR3, non-ECC, 240 pin, etc. The new one is a Kingston brand.

My system is Windows 7 Pro, 64 bit, plenty of free space on the hard drive. I keep the system clean (disk, registry, temp files, virus scans, etc.).

I didn't buy the new stick from Dell, so as to get a better price, in case that's an issue for you helping me with my question. For what it's worth I've owned three Dell systems, two desktops and a laptop.

Thanks again,

Larry

RoHe · Answer

numbered, visibly, from left to right as 3-1-4-2,

Unless there's something special about the 7010 that I don't know, the first RAM module should be in the slot numbered "1". You said yours is in slot #2.

So in this situation, I'd put the second module in slot #1, which should have the same color retention clips as the slot where the original module is installed now.

Keep in mind that your new module may have the same specs as the old one, but that doesn't mean it's identical to a module of a different brand. So if you experience any issues (freezes, crashes, etc) with both installed, you may have to get second Kingston to exactly match the one you just got.

larks2020 · Answer

Thanks, Ron. That helps. Before doing my inquiry here in the forum I did try them both installed right beside each other in slots 4 and 2 (per Dell tech on the phone), and everything seemed to work fine. But I've read that they should be set up dual channel for best results, not right beside each other, so I thought I'd inquire further on the Dell forum here. Since getting your response I've re-slotted the second (new) stick to slot 1, so they're now in the slots numbered 1 and 2 (what I understand to be a "dual channel" configuration).

I'm curious as to why they would have to be the same brand when all the specs are the same (my other stick is Samsung). They seem to be working fine together (either configuration). Can't tell yet if the system is any faster, though, with the new setup.

Thanks again, Ron.

RoHe · Answer

As long as slots 1 & 2 have the same color retention clips they should run as dual-channel.

There's a lot more to RAM than just speed (MHz) and size (GB) and Dell PCs can be very fussy about RAM. Some brands are just better quality and then there's the number of chips on each module ("rank"), latency etc, etc. So mixing brands can make a difference.

It's recommended that modules in the same bank (same color retention clips) be totally identical, and modules in the other bank should also be identical to each other, but not necessarily identical to those in the first bank.

If things are running ok -so far, that's a good sign, but check to see if Windows is recognizing the new total amount of RAM.

larks2020 · Answer

Ah. Good points. My system doesn't seem to be too fussy about the brands being different, at least that I can tell.

The good news is that the System readings are showing 8GB in both configurations, from the moment of installation whether dual channel or "single" channel (where sticks are right beside each other). Not sure what, if anything, to make of that.

And I still can't tell what difference running dual channel is making on performance over single channel. I've had the Task Manager open for both configs for several days and can't tell much which one fills up RAM faster. Seeming pretty even so far, but I'll continue to watch it a few more days under different app loads. I've read that the dual mode config is supposed to be about 10% faster/better/whatever. Can't tell yet.

In any case, looking like I lucked out with the mixed brands (Samsung and Kingston); no problems I can detect.

Thanks again, Ron, for you responses here. I appreciate the clarity.

Locked Topics – Desktops General

Which RAM slot to use for an additional stick

what is ddr3 memory?

memory configuration

dual-channel configurations

memory speeds

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