I have ordered some extra RAM and I know I need to keep in contact with the chassis of the PC to reduce static risks (although I don't have a wrist strap). My specific question is - should I leave the PC plugged in so that it is grounded (switched off at the socket of course).?
These days several parts of the motherboard will remain powered up by the standby power that is available whenever the machine is plugged in, so unless there is a physical power switch on the PSU itself (unlikely these days) rather than a "soft" power button from the motherboard, I'd say disconnect it.
Hold the DIMM/SIMM by the edges only, avoid touching the chips or the contacts, and you'll be fine.
You know, in nearly 40 years in the IT industry, I have never, ever, seen a static-damaged DIMM. The chances are very small that you will have any trouble. Just don't wear any nylons :)
I have. Once. Perceptible 'snap' as we tried to plug it in. Winter,nylon carpet, dry air..etc.
I think that in all my years of plugging chips in and out of other stuff, I can count on the fingers of one hand static damaged stuff..yes, in the early days before they had diode protection on the chips..one or two maybe. Hard to say because when your job is designing stuff, you are buggering around with live circuits and its a tossup as to whether it was static or shorting the pins etc.
Having it plugged in is VERY likely to cause damage these days.
You're not only supplying an earth, you're supplying power to the PSU, which is supplying power to at least part of the motherboard (on a modern motherboard) - even if you think the PC is "switched off".
You really are as clueless as Drivel 8-(
Nor is grounding the PC a good idea anyway - _only_ if you're also grounded yourself, such as through a wriststrap to a bench with an earth terminal. The problem here isn't to "ground" things to earth, it's to stop there being a _relative_ difference between one part and the other, i.e. the PC case ground and your hands. If you're ungrounded by a wrist strap and you're standing on a nylon carpet wearing your best PVC fetishwear, then grounding the PC (but not you) can often make things much worse. Ever walked through a clothes shop on a dry winter day (low humidity, high static risk) and touched the (grounded) hanger rails only to receive a shock through your fingers?
Your best approach is a wriststrap with a croc clip to the PC case.
Your second best (and very good) approach is simply to touch your hands to the PC case steelwork before handling the elctronics.
Hmm, I've just had to replace a fried motherboard and 2Gb of RAM all damaged by static. Some fool decided it would be a good idea to vacuum clean the inside of a server without thinking about how much static a vacuum cleaner can generate or taking precautions to ground the cleaner.
I dare say it isn't 'best practice' - but I agree with you. I get most of my ram chips from the tip, have done for many years now...they get handled, they get carried in pockets, they get shoved into an assortment of machines in various states of powered-upness - and the only time I've ever had a problem was with a stick of memory on a much-abused test-bed machine that gave up the ghost of its own accord after a good few years in service.
Of course, sod's law dictates that as soon as I buy myself some 'posh' ram, complete with heatsinks and go-faster stripes, it'll go 'pop' the moment I take it out of the packaging...
That stuff was actually pretty fragile. The sense amplifier front-end (the single wire that snaked through every core) was a bit of a garage queen in its own right.
He was responding to the OP who said "(switched off at socket of course)". As you consider yourself not clueless, clearly, how does power get to the PSU with the socket turned off?
But do remember John, that it's the static discharge that does the damage (a short peak of quite high current from the high static voltage) and that wrist straps etc have a 1M ohm resistance so that the static voltage can leak away at a controlled rate.
These components all cost too much for the private individual to take any risks. I do get a slight feeling from one or two of the posts that being gung-ho about it in the lab is OK as the company will pay for a replacement. Been there, done it so don't take offence guys - just as guilty.
Clearly one of those Clued-up Google Groups guys, who know everything. Which explains why I didn't see his post (Google Groups filtered out).
The big question, of course, is: Is it Red or Green Electricity? As this will affect the polarity of the static. Which in turn will decide if the diode protection will work or not.
I spent many years working with static sensitive devices and never (bar once) had any problems, despite rarely taking any precautions other than ensuring I was discharged to the equipment.
Ensuring you *and* the equipment are at the same potential is the important thing, not that either is connected to earth.
The one time I had a failure was removing a eprom (personally owned 8-( ) from a supposedly antistatic tube. It noticably flashed over with a crack to my fingers as it exitted the tube.
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