PC Memory

  Kev.Ifty 01:15 06 Aug 2005

I am more of a mechanically minded than computery minded person. Give me a problem that can be solved with a screw driver or spanner (or mallet) and I'm happy.

For a living i repair equipment which is increasingly becoming more computer orientated.

Just recently one of our customers ask us to 'upgrade' some of their machines.

We have to install new hard drives and memory.

Now my knowledge is very limited. I thought you have to fit memory in pairs, but some mother boards that i have come across have three slots. What is the third slot for?

  LastChip 01:26 06 Aug 2005

You used to have to fit memory in pairs on the very early Pentium processors. Without going into a long technical explanation, it was to do with the way the system bus accessed the memory. Today, it is no longer necessary. However, the order in which those slots are used, is likely to be determined by the motherboard manufacturer.

  mec13 01:27 06 Aug 2005

click here recentley asked the very same question just recently. Have a look it will give you all the answers you need. These experts need a rest now and again you know.

  Kev.Ifty 01:49 06 Aug 2005

Cheers LastChip and mec13

mec13 ya 'clickhere' aint working ;-)

Thanks Kev.

  Totally-braindead 15:54 08 Aug 2005

Just to confirm what has already been said by Lastchip memory did used to need to be upgraded in pairs but this is no longer the case and hasn't been for quite a few years. This is why you notice 3 slots rather than the 4 that used to be on motherboards. To upgrade the memory it should be just a simple case of putting in some memory to the next available free socket, but the memory will have to be the correct type for the system.

  freaky 11:32 11 Aug 2005

I am using a Asus A8V De-Luxe MOB which was new in December 04. This have 4 memory slots which are colour coded (blue & grey). It states in the manual, that if for example two slots each have 2 x 256 memory chips and you want to upgrade by 1024. Then you can either add 1 x 1024, or 2 x 512mb. If you decide on 2 x 512mb, then they MUST BE A MATCHING PAIR.

In this example the MOB uses PC3200 DDR-Memory (400MHZ). Therefore in some of the replies above where members state "used to be upgraded in pairs but is no longer the case" is not necessarily true in all cases. The moral is check your MOB website before doing any memory upgrades!

  LastChip 12:49 11 Aug 2005

The fact that you can use (in you're example) either one slot of 1024MB or two 512MB confirms you can use one OR two slot to achieve the same goal.

The only reasons Asus says "use a matching pair are,

1. Sometimes different manufacturers modules do play well together.

2. It wouldn't be wise to fit for example a 400MHz chip with a 266MHz, as this would slow down the overall performance of the motherboard (MB) bus, if it would work at all - (some wouldn't).

3. Some late MB's offer a dual channel option, that allows both chips to run simultaneously, increasing available bandwidth. This is more efficient, but again, one chip can be fitted if speed is not a priority. Clearly, in order to maximise performance, it is logical to use a matching pair. This option may apply to your MB and could be the reason for the Asus statement.

Never-the-less, in general terms, my original statement holds true.

  freaky 18:59 13 Aug 2005

Yes you are quite correct, my MOB is dual channel hence the mention of matching pairs in the manual.

  harps1h 23:33 13 Aug 2005

i have the same board but what i find is that although i have the same memory bought from crucial they will not work together in the first two slots only in the second two, thus running in single channel only. if i try to put them in the dual channels the computer refuses to boot

  harps1h 23:35 13 Aug 2005

meant to add that they were bought at different time althiugh they had the same product number on the web site and were for a dfi mobo which i just replaced with the above

  freaky 10:36 14 Aug 2005

Thats probably the cause then, I used the Crucial Tool to check and recommend what I needed. It recommended either 1 x 1024 or a matching pair 2 x 512. I got the pair and installed in the two spare slots.....worked OK.

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