how to choose 2-pair or 1-pair RAM?

if buy RAM , is look 2-pair 2GB+2GB or 4GB 1-pair , which is better?
any advice please!

 

I am not sure you are seeing this right - or maybe it is just me.

Note that 2 pair = 4. So with 2 pair, you get 4 sticks of RAM. 1 pair is 2 sticks.

So are 4 sticks better than 2? Are two sticks better than 4?

As Arie noted, it depends on your specific hardware - the motherboard specifically.

But generally, if your motherboard supports dual-channel memory architecture, you need to install in pairs. Either 2 or 4 sticks (if your board support 4 sticks). In terms of performance, it does not matter if you go 4 x 2Gb for 8Gb, or 2 x 4Gb for 8Gb. Except maybe on your budget.

Oh, it does take more power to run 4 sticks, and 4 sticks generate more heat than 2.

 

Hi my experience has been that 2 supported memory modules will often additionally enable a memory process which effectively doubles internal bandwidth for something like 10% faster overall system processing, so is "better" than a single larger capacity - which will not support this process
This processing function is called "dual-channel architecture" and my understanding works similar to a RAID striping array hard disk drive implementation
Retail memory items for dual-channel are called Kits so a 4GB kit will be 2 x 2GB modules
Also often 2 x 2GB modules will be cheaper cost than 1 x 4GB module , especially if used,
or 4 x 1GB - (if the main board supports 4 modules) will be often be very cheap cost (thinking ddr2 memory)
Some budget computers use a single module that will not support dual-channel processing even if another module is added so if not installing a dual-channel Kit , after for example adding another single module check dual channel enabled via notation on BIOS splash screen at system power on , BIOS setup or use a utility program such as cpu-z , You might have to replace the oem module if maximum performance is desired
This should not be an issue for higher level computer models and all workstations
If using Windows VISTA/7/8 32bit i suggest 4GB total if supported as this enables maximum system memory allocated for video rendering.

 

If your motherboard is capable of using Dual-channel architecture, two matching modules will give you the best performance.

If your motherboard is capable of using Triple-channel architecture, three matching modules will give you the best performance.

If your motherboard is capable of using Quadruple-channel architecture, four matching modules will give you the best performance.

Crucial.com's Memory Advisor or System Scanner can help you figure out which type you need.

 

Adding memory to existing setup.

Is there a correct procedure when adding memory modules? My Compac Presario CQ5115uk memory connector is four slots, occupied/empty/ occupied/empty. I am thinking of buying 2x2Gb DDR2 modules, do I insert new modules in the two unoccupied slots?

 

See: http://h10025.www1.hp.com/ewfrf/wc/document?docname=bph03886&cc=us&dlc=en&lc=en&product=3986409

1. Unplug the computer from the wall and 2. touch bare metal of the case interior BEFORE reaching in and frequently thereafter. This will discharge any static in your body, putting you and your computer "at the same potential ", thus minimizing potential device destruction from ESD.

 

If you unplug the computer mains cable from the wall socket, no longer is your computer metal case earthed.

 

Doesn't matter. The case does not need to be grounded and you don't need to be grounded. You need to be "at the same potential" as the case. If there is "no difference in potential ", there can be no flow of current. Thats a fundamental law of electronics.

So to the point of leaving a computer plugged in for the ground or "Earth ", that is an old wives tale - never endorsed by anyone in electronics with any formal training. It is a bad, very unsafe practice for many, many reasons.

1. It assumes the facility wiring is properly grounded to "Earth ".
2. It assumes the wall outlet is properly wired to facility ground.
3. It assumes a $.25 "power" cable is providing a proper ground.
4. It assumes the computer PSU is functioning properly, with no malfunctions or damage from abuse or accident.
5. It assumes the PSU has a proper "mechanical bond" to the PC case - essential to ensure a good electrical connection.​

Unplugging from the wall assumes nothing, EXCEPT the same potential!

Remember, your car is not earthed. Neither are airplanes. They don't need to be, to be safe. But that does not mean they are not properly grounded.

You should never - as in NEVER EVER trust your life to a cheap power cable and assume it provides a good ground. If you need grounding to Earth when doing maintenance on electronics, including computers, you should always use a grounding strap designed for that purpose.

Also, for the last 10 years or so, the ATX Form Factor standard calls for the ATX PSU to provide +5Vsb voltage whenever the PSU is plugged in, but the computer is shut down. This "standby" voltage is used to power the various "Wake on..." commands when your computer is off. These include Wake on Keyboard, Wake on Mouse, Wake on LAN, Wake on Modem.

This voltage is also used to keep memory "alive" during some sleep modes.

If you attempt to plug in, or unplug RAM with that SB voltage present, you have an excellent chance of destroying your RAM.

The standard does NOT require a master power switch on the back of PSUs. That is optional and many PSUs do not have one. If your PSU does not, it IS supplying +5Vsb to several points on your motherboard, including your USB ports whenever it is plugged in.

Never plug in, or unplug anything from your motherboard with power present unless it is specifically designed to be "hot-swappable ". And no motherboard RAM is.

 

you are supposed to be wearing a grounding strap which is connected to a known good earth - this discharges very high potential voltage from ones body which renders the touching of voltage / current sensitive components relatively safe.
Walking over carpet can generate and accumulate several thousand volts of static-charge within an inept user sub-system

 

Bill, do you mean "polarity "? It is the current value needed to make the voltage a danger level.

 

No. It is all about "potential" - which is measured in volts. In the case of electro-static discharges (ESD) it is typically 10s of 1000s of volts. 30,000 - 50,000 volts of static can easily be generated by the human body squirming in our clothes while sitting in our chairs, or shuffling across a carpet. However, it takes much much less than that to destroy sensitive devices.

Understand ESD sensitive devices include devices like memory modules, GPUs, CPUs, and other "high-density" (100s of millions, or billions of transistors in one chip/IC) devices. With billions of transistors in one small device, you can (maybe - I cannot) image how small each transistor must be.

The greater the gap, the higher the voltage (potential) must be in order for the voltage to jump (arc across) the gap. Lightning (which arcs miles) is in the millions of volts. When you zap a doorknob, that may be 40,000 volts or more.

The tiny size of each transistor means there is even a tinier gap (insulator) between the conductors and each transistor. Tiny (microscopic) gaps can easily be jumped by a static discharge of just a few 100 volts or less, which is way more than enough to destroy (burn!) ESD sensitive devices. Some devices can be destroyed with a potential as small as 30 volts!

The problem with ESD and humans is the "threshold of human awareness" is somewhere above 3000 volts. This means a static discharge from your fingertip can easily zap and destroy your RAM, CPU or other devices on your motherboard without you even knowing a shock occurred.

I have seen estimates that say more than half of all warranty returns for DOA RAM and CPUs can be attributed to poor ESD control by the user destroying the devices during installation and handling. It is a big problem.

Yes, but we are not talking about danger to humans, or ESD discharges the size of lightning bolts - but static charges much less than that affecting super-vulnerable, microscopic, ESD sensitive devices inside ICs.

That is not discounting the current. It can easily exceed 10s of amps (amperes). But electro-static discharges typically last 1 nanosecond or less, plenty long to destroy microscopic transistors, but not enough to hurt (or be noticed by) monster humans.

***

No, sorry but that is not true for the vast majority of users. Unless you are a qualified technician, or you hire a certified electrician, it is highly unlikely you have access to a "known good earth ".

Where is the "normal user" supposed to find such a thing? The wall outlet again? No! Don't do it!

Unless the user is a qualified electronics technician or certified electrician, it is highly unlikely he or she would know how to determine a "good earth" or has the required test equipment to determine a good earth. Note a proper earth ground NEVER runs in the same cable as the power.

DO NOT ASSUME your home or facility wiring is properly grounded unless it has recently been properly tested and certified. Passing a building code inspection when the building was new is not a proper test or certification. When I maintained air traffic control radio equipment, our facilities and benches were tested and certified annually. Many people like me, live in older homes. Many rent, and have no control over any of that.

You need to establish a "floating ground" to put you and the computer "at the same potential ". A floating ground is ideal as it is highly effective at isolating (thus insulating) you and the computer from everything else, while maintaining "no difference in potential ".

With a floating ground, you are grounded to the case, and the case (and components inside) are grounded to you. Zero difference of potential, no flow of current, no ESD!

You can certainly use a anti-static wrist-strap attached to bare metal of the case. Many shops and certainly high-tech labs require them - even though all their workbenches are properly grounded, tested and certified too. If you work on sensitive equipment a lot a good wrist strap is a good idea as they prevent static buildup in the first place. Otherwise you MUST be disciplined to touch, and keep touching bare metal to discharge yourself.

However, a poorly fitting, worn-out, damaged wrist-strap can give a false sense of security, but no protection from ESD. So I personally prefer using my finger planted on bare metal. That way, I know I am making contact. But it MUST be a disciplined habit to ALWAYS touch metal first, before reaching in.

 

interesting post , for those concerned about mains power earth integrity
Some auctions list low cost test devices such as
POWER POINT ELCB EARTH LEAKAGE RCD SAFETY SWITCH TESTER @ $25

faults the unit will display are:
No earth connected
No neutral connected
No active connected
Active and neutral reversed

 

Those testers are not suitable for here. While Earth "leakage" is a safety concern, it is not really an issue here for this discussion as again, we are not looking for Earth ground, but a floating ground.

That's just another beauty of floating grounds - they are totally independent, isolated, and unaffected by your facility ground (or lack of it).

That said, when your computer is connected to the wall outlet, it is good to know the outlet is properly wired. So I recommend every homeowner, home renter, and computer owner have a AC Outlet Tester. I recommend one with a GFCI (ground fault circuit interrupt) indicator as it can be used to test bathroom and kitchen outlets too. These testers can be found for your type and voltage outlet, foreign or domestic, at most home improvement stores, or even the electrical department at Walmart. And note the GFCI feature serves as your leakage tester too.

 

Hi, if the sockets are paired by color you have to use two sticks "I think" if they're not you don't? But sometimes they're numbered or lettered as well and the board specs tell you to use "A+b only first, then C+D" or "1+2 first etc "

Anyway nice to see we have a few "Sparky's" here and the talk of ESD and potential difference.

I sometimes get asked why birds sitting on a high voltage line "200,000V + don't get fried,
and of course the fun trying to get it through to the person asking. LOl

No return path to earth of course and have any of you seen the guys working on the HV pylons?

When the helicopter gets near they hold out a conductive probe and touch the cable to equalize the potential difference.

Recently some worker forgot and he was killed, don't whether the current passing through his body killed him or the fall!

Never in over twenty years have I ever killed anything with static but I know a guy who only has to walk across a carpet and you get a shock off him, type of shoe materials make a difference as well.

As the people here have said, if you touch the case your safe.

Thanks, Ian.

 

No. You do not have to. But for motherboards that support dual channel memory architecture, to enable that performance boosting feature, the sticks do need to be in pairs, and in the correct slots.

There is no standard as to which pair (and no standard colors either). So read your motherboard manual. If you have 4 slots, some require you use 1 and 3, then 2 and 4. But other boards say to use 1 and 2, then 3 and 4.

In any case, if you use just one stick, or put them in the wrong slots, you will just run in single channel mode. No harm is done.

Also, some motherboards support triple channel so RAM will need to be installed in triplets.

Same reason you will not get fried if you grab hold of just one wire, and your feet are off the ground - you are not completing the circuit - or as you noted, no return path.

Touch another wire, or the ground, there will be a "difference of potential" (200KV vs 0V in your example) and instant smoke.

That is the problem squirrels have - they forget to let go with their hind legs before grabbing with their front. Puff! Usually accompanied by a very loud bang, and 90 - 120 minutes of no power until the power company comes and resets the transformer, or replaces the fuse.

Oh? I say you would not know that.

That's the problem with ESD, and why it remained so mysterious for many years. Integrated circuits (ICs) like RAM, CPUs and other devices can very easily be destroyed by a static discharge so small, you (as a human) are incapable of detecting a static discharge even occurred. Your eyes are incapable of detecting such a tiny arc, your ears are incapable of detecting the "snap" of the spark, and even the most sensitive fingers are incapable of feeling any spark. Yet a static discharge so large as to burn a Grand Canyon size swath through dozens, or even 1000s of transistors could have EASILY occurred, if proper precautions were not observed.

It took microscopic analysis of 1000s of returned products (that passed testing leaving the factory) to first, see the microscopic damage, then much longer to determine it was users (at the time, ONLY highly trained electronics technicians) mishandling these products.

So while you think you have never killed anything, there is no way of knowing for sure, unless you have never handled any ESD sensitive device.

You must emphasize, "bare metal" of the case. Not plastic, and nothing painted.

 

Thanks the info on memory very useful for the future!
Like someone has said down the line "read the instructions ", I suppose the little piece of paper that came with say the motherboard gets lost.

When a home is fitted with a new consumer unit the owners think that it's impossible to get a shock, which substantially reduced I agree, compared to our old BS 3036 fuse boards.
Like with the squirrel if you touch live and neutral you become the load and applies to isolation transformers used in shaver sockets for bathrooms.

Yes I've seen the damage caused by ESD to a MOSFET, it's like a volcano has erupted.

I suppose being taught never touch the pins, handle the part by the non conductive areas, don't walk across the carpet carrying it unless It's in a anti static bag has helped over the years and It's surely common sense to touch a bare metal part of the casing.

There have been a lot of cable thefts etc here in the UK, the police turned up to one and found a foot in a boot melted and stuck to the floor. "Off Piste" a little sorry.

It's always good to learn something new and when I get my new sever ram I'll be extra careful thanks.

Regards Ian.

 

just to make matters worse , my understanding is that static damage can degrade component performance without it testing failed when using consumer test methods or being obvious in use.

 

Every new motherboard I have bought in the last 15 - 20 years or so came with a large booklet, detailing how to safely handle, install, connect, configure, and use the motherboard. And every major motherboard maker maintains documentation for their products for download on their sites. I frequently recommend buyers download their motherboard and graphics card manuals BEFORE receiving them, to become familiar with them while waiting for delivery.

I have never heard that. Got a link? Understand that a static discharge (a static shock) is a tiny lightning bolt of intense heat that literally burns a path through the junctions of 100s or 1000s, or even millions of microscopic transistors. Remember, CPUs and GPUs typically have 100s of millions, or even several billion transistors in the space of a postage stamp. RAM sticks (with 8 to 16 memory modules per stick) can have many more than that! It takes just one bad transistor to render the IC dead.

A zapped IC is zapped dead.

 

my understanding is that a single chip on a memory module can become static damaged yet the rest of the chips relating to memory space from that faulty chip to the top most memory space will function ok - just reduced total installed memory
Unfortunately I can not recall or find the information source