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This is a guide to upgrading and/or installing memory. There seems to be a lot of confusion, so I'm posting just about everything you'll need to know.

Determining what type of memory you need:
This can be done three ways. First would of course be take out the stick and look for a sticker with all the information listed on it. Almost all sticks have at the bare minimum a serial number which you can look up using google.com. The second would be using manufacturer resources. Looking up what the specifications are using the manual, looking up the information on the manufacturer's website, or finding a listing perhaps on a sticker that's on the outside of the computer case. The third would be www.crucial.com, but you need to know what motherboard you are using, which you can look up using the aforementioned manufacturer steps. The kinds of things you want to look for are going to be it's clock rate. It will be rated as either PC#### or DDR###(# = number). IE PC3200 = DDR400 = 400MHz clock rate. Here's a list of memory clock rates and their equivalencies:

PC RATING DDR RATING CLOCK RATE

DDR2 (Double Data Rate Revision 2)

PC2-10000 = DDR2-1250 = 1250MHz
PC2-9200 = DDR2-1150 = 1150MHz
PC2-9136 = DDR2-1142 = 1142MHz
PC2-8888 = DDR2-1111 = 1111MHz
PC2-8800 = DDR2-1100 = 1100MHz
PC2-8500 = DDR2-1066 = 1066MHz
PC2-8000 = DDR2-1000 = 1000MHz
PC2-7200 = DDR2-900 = 900MHz
PC2-6400 = DDR2-800 = 800MHz
PC2-6000 = DDR2-750 = 750MHz
PC2-5400 = DDR2-675 = 675MHz*
PC2-5400 = DDR2-667 = 667MHz*
PC2-5300 = DDR2-667 = 667MHz*
PC2-4300 = DDR2-533 = 533MHz*
PC2-4200 = DDR2-533 = 533MHz*
PC2-3200 = DDR2-400 = 400MHz

*PC number varies based upon manufacturer labeling

PC RATING DDR RATING CLOCK RATE
DDR (Double Data Rate)

PC-4400 = DDR-550 = 550MHz
PC-4000 = DDR-500 = 500MHz
PC-3500 = DDR-433 = 433MHz
PC-3200 = DDR-400 = 400MHz
PC-2700 = DDR-333 = 333MHz
PC-2100 = DDR-266 = 266MHz

SDRAM (Plain)
PC RATING CLOCK RATE
PC133 = 133MHz
PC100 = 100MHz
PC66 = 66MHz (very old)

The next thing is its timing. Don't worry a terrible amount if you can't find this. The rating should come as #-#-#-#-#T (IE 2-3-3-5-1T) Here's a brief rundown of what these numbers are:

2 = CAS Latency (Column Address Strobe)
3 = tRCD (RAS or CAS Delay)
3 = tRPD (RAS Precharge)
5 = tRAS (Number of clock cycles between bank active command and the issuance of a precharge command)
1T = Command Rate (Per row activate command)

Most of this terminology will be very foreign I posted this for people who had questions about memory latencies. Most RAM will configure to slower timings for different boards, but check the RAM manufacturer website before making any purchasing decisions as they will have documentation on known problems, as will the motherboard manufacturer. Next I will describe memory setup.

After you have made sure all of the specs are correct, and you have chosen the amount of memory you wish to upgrade, you need to know how many slots on your motherboard you have to upgrade with, and what the maximum memory is for each slot. Again, you should either check with your motherboard manufacturer if you bought the motherboard separately, or you should check with the computers manufacturer to find out these 2 things. Once you have determined these, go ahead and install the memory.

Additionally there have been questions about Dual Channel capable motherboards. While you can use 2 different manufacturer's (with the exact same specifications) it is going to be easier (and cheaper) to just get a set from one manufacturer. I will describe setups that are usable with various slots on different dual channel boards.

Setup #1:

[============Dual Channel 1 Slot 1============]
[============Dual Channel 1 Slot 2============]

[============Channel 2 DIMM===============]

If you wish to operate without Dual channel memory, you MUST only use Channel 1 Slot 1 and Channel 2, with nothing in Channel 1 Slot 2. You can operate with both Dual Channel, and a DIMM in Channel 2 or just Dual Channel, but only when using Dual Channel should you ever put a DIMM in slot 2.

Setup #2:
[============Dual Channel 1 Slot 1============]
[============Dual Channel 1 Slot 2============]

[============Dual Channel 2 Slot 1============]
[============Dual Channel 2 Slot 2============]

To be able to operate without dual channel here, you can only place DIMMs in Channel 1 Slot 1 and Channel 2 Slot 2. To use any of the other slots, you need to use Dual Channel memory in that channel. Additionally, if you want Dual Channel and 1 separate DIMM, make sure you use Channel 2 Slot 1 as the additional, with Channel 1 in Dual Channel mode.

I hope this answered most, if not all of your questions regarding memory. Thanks and have fun! :lol:

(PS Sticky appreciated here as well thanks! :lol:)

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Last Post by dcc
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When you mentioned Crucial you said that you would need to know what the motherboard is, that is only one to the two ways you can search there. You can also search by entering the make and model of your computer. You can also use a utility like SIW (System Information for Windows) to find out what you have for RAM, the capacity, and the number of expansion slots.

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When you mentioned Crucial you said that you would need to know what the motherboard is, that is only one to the two ways you can search there. You can also search by entering the make and model of your computer. You can also use a utility like SIW (System Information for Windows) to find out what you have for RAM, the capacity, and the number of expansion slots.

looks like a nice program ,will it actually tell the capacity of ram my board will take .never mind ,i downloaded it and ran it i guess it does,it says cap is 512 ,i assume it means per slot .as i have 768 installed in 2 slots

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looks like a nice program ,will it actually tell the capacity of ram my board will take .never mind ,i downloaded it and ran it i guess it does,it says cap is 512 ,i assume it means per slot .as i have 768 installed in 2 slots

If you go to Memory under Memory Summary you will find the current capacity of RAM installed, below that it lists the motherboards capacity, the number of expansion slots, and the maximum module size.

Below that it will list the information on each RAM module slot by slot. This includes its capacity, memory type, speed, data width, form factor, and total width.

This is a great utility, it is one of three that I keep. I also keep Everest Home Edition, but it is not as reliable about finding information. If you go to mother board and choose SPD it will usually give the manufacturer of the RAM modules and their specs, it will do this with my old machine but not my new build.

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if im reading this right then it has the wrong info for my board ,max memory module size as 32meg.

Property Value
Model P4M266A-8235

Chipset Vendor VIA Technologies Inc
Chipset Model VT8751 ProSavageDDR P4M266 System Controller
South Bridge VT8235 PCI to ISA Bridge
SMBus VIA Technologies Inc VT8235 PCI to ISA Bridge @0500h

CPU Intel Pentium 4
Cpu Socket Socket 478
Processor Upgrade ZIF Socket

System Slots 3 PCI, 1 AGP

Memory Summary
Location System board or motherboard
Maximum Capacity 512 MBytes
Memory Slots 2
Error Correction None
Use System memory
Maximum Memory Module Size 32 MBytes

Warning! Accuracy of DMI data cannot be guaranteed=

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That's weird, this is the first time that I've seen a discrepancy like that. It would be interesting to learn why this happened with that board, if I have time this afternoon I'll try calling to see what gtopala has to add. I had seen the disclaimer, I just had not seen anything but great results before this.

Did you find any other discrepancies.

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