Leave the last RAM slot alone?

[vinunleaded]

I was informed by a friend of mine that we should not use all 4 available RAM slots on the motherboard even on high end computers because it would cause some sort of problem. Is this true? Can anyone confirm this?

[nphsbuckeye]

I don't know much about the situation with RAM in mobos, but high end mobos have 6 DIMM slots these days. So, that statement seems a little old. Plus, I know many people put 6 DIMMs on their mobo, thus giving them the 12 gigs. Finally, I can't imagine a high end mobo having an option the user can't use.

[tkbslc]

Ridiculous assertion. I have done it many times and I have many servers I manage at work with all the RAM slots full. Several have been up and running continuously for over a year. I have one server with 16 slots and I have filled them all.

Also, if you have 4 slots and leave only one empty, you will not be taking advantage of the dual channel features of your memory. This requires pairs of memory. So use 2 or 4 sticks and ignore your friend.

[CaptainK]

I was informed by a friend of mine that we should not use all 4 available RAM slots on the motherboard even on high end computers because it would cause some sort of problem. Is this true? Can anyone confirm this?
That's ridiculous. That is definitely not true.

I have 3 desktop machines(4gb, 3gb, 2gb) , 1 laptop (2gb) and and one server with 8gb. Not one free slot to be had amongst the whole lot.

[Fut]

Sounds to me like an "April Fools" joke.

Fill it my son, fill it !!!!!!

[RandyMN]

We do it all the time at work and home.

Perhaps it has something to do with always replacing RAM in pairs. Sort of like the telephone game where the end message was nothing like the original.

[Quad]

It could be in reference to a motherboard that is using tri-channel memory but has four slots like some i7 boards. The memory would revert to dual channel mode with the four slots occupied and may cause a slight slow down in memory operation.

In practice I do not think memory is running fast enough yet to make difference between dual and tri channel mode.

It would not cause a problem like system crashes though.

[ChasP505]

I never heard of such a thing, but with every computer I've ever owned or built, I only use perfectly matched sets of ram.

[CyberDyneSystems]

I was informed by a friend of mine that we should not use all 4 available RAM slots on the motherboard even on high end computers because it would cause some sort of problem. Is this true? Can anyone confirm this?

This sounds like some very old and very specific info.
In the days of SDRAM, (not DDR) many Mobos , Athlon Mobos in particular, would have four DIMM slots. However, at the same time, many did not have the proper horsepower to supply consistent voltage to all four slots.
(remember with SDRAM back then, the whole idea was to put your "pair" on a single DIMM,. "D" standing for "dual", so you did not work in pairs, the single stick was a pair)

Anyway, on some very popular Mobos like the famed Abit KG7-Raid, using the 4th DIMM slot was a hot or miss game. Sometimes it worked fine, sometimes it would not, sometimes it would slow things down.

None of this applies to any more as far as I know.



However, the other factor was touched on above, and may apply in some cases.. Now we seem to have moved back to multiple slots or sticks of RAM making up a bank..
To get that bank working best, one needs to use matching dimms within that Bank.

SDRAM: took us from pairs of "SIMMS" (single in line memory modules) to DIMMS (Dual Inline Memory Modules) and alleviated the need for buying in pairs for about a decade!

DDR: With DDR1, we still did not need pairs in the vast majority of cases, however in some applications (Opteron Server boards for example) we had "Bank interleaving" , "Dual channel" and other such names,. where pairs or groups of four were best again.

DDR2: With DDR2 we moved back to a pair of slots making a complete Bank in the majority of platforms, as Dual Channel memory controllers became the norm. In that case with four slots on a Mobo you'd want either four of a kind, or two pair. Yes there are DDR2 Mobos that aren't dual channel.. or you can use unmatched pairs and not use the performance boost that Dual channel offered.

DDR3: brings us up to banks of THREE slots...
Some Mobos are Dual channel, some are triple channel.
That's where I could see this leading to a performance hit (in some measurements) from adding the fourth odd stick in a triple channel board....


However in most cases more RAM outweighs the slight performance hit that having odd amounts of slots populated.

[Zepher]

on some older boards when DDR just came out, you would have 2 SDRAM Slots and 1 or 2 DDR slots. you could only use 1 or the other so either 1 or 2 SDRAM or 1 or 2 DDR, but not both at the same time.

Some of the newer boards are doing the same thing, 4 DDR2 and 2 DDR3 slots and you can't mix and match, you have to use 1 or the other.

http://www.transamws6.com/pics/pc/2009/ddr3.jpg

[Rodinal]

I was informed by a friend of mine that we should not use all 4 available RAM slots on the motherboard even on high end computers because it would cause some sort of problem. Is this true? Can anyone confirm this?

Absolutely true on computers with manufacturer's documentations that says so.
Absolutely BS on the others.

Go back to your friend and ask him to define "some sort of problem".

[sangosimo]

some motherboards have stability problems when all four slots are filled. I had to lower my overclock when I filled up all my ram slots .

[Zepher]

some motherboards have stability problems when all four slots are filled. I had to lower my overclock when I filled up all my ram slots .

That is not a problem with the board.

[CyberDyneSystems]

Absolutely true on computers with manufacturer's documentations that says so.
.....

Seriously? There are Mobos out there that KNOW they can;t use all slots, but still give you that slot to fill anyway?

Why?

[Frank_The_Tank]

My last motherboard died after fitting a second pair of ram sticks that have been sitting redundant in my drawers for months, to the two remaining RAM slots. BIOS resets proved fruitless and my buddy who is an excellent IT tech had no more luck than me. Possibly too much current for the power section to handle? Who knows... It wasn't exactly high spec