RAM question

[Scott]

I'm thinking about an upgrade. Is there anything to choose between Crucial and Kingston? Similar price. Thanks

[Theo]

Crucial is the retail brand of Micron, who are a big DRAM manufacturer. Kingston don't make their own DRAM but buy silicon on the spot market (although in big batches) and do their own packaging. That means Micron have more control over the product whereas Kingston can change DRAM supplier based on supply chain.

When I spec stuff for areas that need precise control over parts I go for Micron, but in reality for general PC use either will probably be fine. I've happily fitted Kingston in random machines when the spec has been acceptable and the price has been right.

Theo

[Davidm]

Just make sure that you buy from a reputable supplier and that they are genuine Micron or Crucial, not some chinese look alike (like eBay and Amazon shops can sometimes be).

[Bob Eager]

I'd be happy with either. But at least you can buy direct from Cricial/ Micron.

[Peter Johnson]

I once ordered Crucial from Amazon because it was a couple of £ cheaper and it came from Crucial. The last time I ordered from Crucial, a couple of years ago, the order came from a warehouse somewhere in Eastern Europe and took ages to get here, by carrier. It would have been quicker if they'd put it in the post.

[Brian Gaff (Sofa]

No, I think they are both made by the same lot in any case. Brian

[Scott]

Thanks. I have ordered Crucial. It was slightly cheaper anyway. .

[Paul]

No more Kingston for me. <=== failures

And there's better than Crucial out there too.

Crucial has two types: Speed binned enthusiast memory (Ballistix brand) <=== one failure Regular (JEDEC speed) memory <=== zero failures

*******

The song remains the same.

Read the customer reviews on the web site, before you buy.

One problem with Kingston, is their contractors will fill orders with either low density or high density modules, when the Kingston PDF spec sheet says they are low density. This is absolutely a no-no. You don't do that, if you expect to remain in business.

This means, if you buy Kingston, two packages of product, one package could have 8 chip DIMMs, the other package could have 16 chip DIMMs. The spot market price for DRAM was crossing over, so one week, the high density chips were cheaper, the next week, the low density chips were cheaper.

For enthusiast memory, there are better brands than either Kingston or Crucial. Sort on the website by "best reviews" and you'll see.

Paul

[Scott]

Thanks. I ordered Crucial yesterday, so I hope it is of the second type.

As a supplementary, does RAM retain any data at all once it is disconnected? Can I safely give the old RAM to a charity shop?

[Adrian Caspersz]

Yeah, if you buy though an ignorant third party box shifter.

Density is related to Rank, need to specify the package part number when ordering, which includes it. Otherwise you will be at the whim of ya supplier.

Some computers have rank limits. Using high density chips allows less of them per DIMM, which means less electrical loading on the motherboard memory bus.

[Paul]

You're not getting it.

There are a number of cases, where a motherboard needs a low density DIMM.

Not all 2GB DIMMs register as 2GB DIMMs.

This has to do with RAS-CAS-BA not having enough bits on the memory controller, to access a high density (low chip count) DIMM.

A module with 8 chips, the chips have twice the density of a module with 16 chips. This requires an extra address bit on the controller. The end result, is an 8 chip DIMM plugged in, registers as having a size of 1GB, if that extra address happens to not exist. There are at least three generations of hardware where this is a problem.

How this works, is the BIOS has two sizing methods. First, it reads the SPD. The SPD says the DIMM is

2GB. But, the BIOS is clever. It uses the legacy peek and poke method as a backup. It executes this method at that point in time. The peek and poke method notices that addresses above 1GB are not working (that's because there is no address bit to select the top half of the DIMM). The declared size of the module, stored in a BIOS table, is changed to 1GB.

This is why the BIOS seldom crashes. It's very careful when sizing RAM and it doesn't make mistakes. The user may be shocked or surprised, to find a gigabyte of their memory has gone missing, but the machine booted and worked and did not crash. Score one for engineering. By using two sizing methods, and one of the sizing methods being a functional test, the BIOS gets this right.

When Kingston ships the wrong DIMM, substituting the 8 chip module when the buyer (me) knows the job needs a 16 chip module and the Kingston PDF said it had 16 chips, now I have to clean up the mess when the customer notices I "short-sheeted" their RAM. Notice how I look bad, like I'm a scammer ? The 8 chip module has to be removed and replaced with the proper 16 chip module.

Now, do you want to do business with them ?

You can't always see what's under those covers. Removing a cover violates the warranty, and you lose your ability to return the product. You can only collect symptoms after it happens, and "guess" that a density mistake has been made. After the PDF was consulted and everything.

Paul

[Theo]

Are you buying from Kingston direct? And ordering a specific part number (KVR32S22S6/4), rather than a specification (like DDR4-3200 CL22)? And they're changing the thing inside the box but with the same part number?

In other words you have two packages with the same part number on the outside but different hardware inside?

Theo

[Paul]

With any luck, you will see two labels. One label has "Micron" on it. The second label has "Crucial" on it. This is a "regular" DIMM and could be what you ordered.

If the module said "Crucial" on one label and was Ballistix branded, then that has slightly different sourcing and speed-sorting. I don't think Micron shows on those. It's been quite a while since I've bought these items, so I'm just going by my defective memory.

*******

And yes, the old memory is safe to give to a charity shop.

The following is if you want to know of a potential issue.

Technical details

"DIMM memory modules gradually lose data over time as they lose power, but do not immediately lose all data when power is lost.[2][9] Depending on temperature and environmental conditions, memory modules can potentially retain, at least, some data for up to 90 minutes after power loss.[9]

With certain memory modules, the time window for an attack can be extended to hours or even weeks by cooling them with freeze spray. Furthermore, as the bits disappear in memory over time, they can be reconstructed, as they fade away in a predictable manner.[2]

Consequently, an attacker can perform a memory dump of its contents by executing a cold boot attack. The ability to execute the cold boot attack successfully varies considerably across different systems, types of memory, memory manufacturers and motherboard properties, and may be more difficult to carry out than software-based methods or a DMA attack.[10] While the focus of current research is on disk encryption, any sensitive data held in memory is vulnerable to the attack.[2]"

Now, you can see there, that none of the special conditions used to make this look like a problem, apply to you. The RAM will be sitting in your room for quite some time, before the charity shop receives it. You will not be throwing liquid nitrogen around the room with abandon.

The spec on a memory chip, might be "please refresh this RAM every 64 milliseconds". The refresh controller is programmed by the PC, to a specific frequency of refresh. The refreshes are multiplexed with your computer programs read/write of memory.

The 64 milliseconds is the time it takes for the "capacitor storing a data bit, to drain off". But the real storage interval (the engineering margin), is probably an order of magnitude or two at room temperature. In fact, some kooky enthusiasts, changed the refresh interval and slowed the refresh frequency, in the believe that the extra 0.1% of performance was somehow important. So there were kooks in the past, in certain forums, who tried these experiments, backing off on the refresh setting until dram-draining errors appeared. But in general, this behavior and practice is not recommended :-) Because it's too kooky.

Your memory will drained back to the random startup pattern. I used to view that pattern in the lab, using MacsBug. And in the DRAM in that era, the pattern of 0xFF and 0x00 tended to reproduce each time the power cycled. It tended to have the same appearance each time - if previous data had affected the pattern, it sure wasn't showing up in my experiments. Of course modern RAM cells are now a thousand times smaller than the ones I was working with, so anything is possible.

While there was a general pattern to what I was seeing, there would also be "defects" in some of the clumps of ones or zeros, so it's not like the pattern was simple enough I could draw it in this posting for you. That would not do justice to the pattern.

By the time the charity shop gets it, it will have faded away.

*******

If you are a paranoid person, that's OK too. You can use memtest before shutdown and removal, and that will generally piss all over the RAM and no personal information will remain. The download is half way down this web page. Prepare the media, of a type suited to booting your computer. Once booted, it starts the test all by itself. You can pull the media out of the machine while the test runs (the program loads from the media at the start, there will be dots on the screen). Once loading is complete, the media is no longer consulted.

You can press the <Esc> key at any time, to stop the test and cause the computer to reboot. You can press the BIOS entry key, enter the BIOS and shut off the power, then remove the RAM when

*all* power is removed. Unplug the computer!

Since the program has progress indicators, it won't be that hard to tell how much RAM has been erased. While the entire test suite might take 15 minutes to run, probably even 1 minute of that will have touched all RAM. Just watch the block address for the evidence of what is being written.

*******

Ideally, you would use an antistatic strap while installing the new RAM. (That consists of a 1 megohm resistor in series with a piece of wire, it's not just a piece of wire.) The alternative is:

1) Wear your summer shorts, with bare legs.

2) Flip the PC onto your lap, with side cover removed. PC is unplugged. The PC ground is now at the same potential as your skin.

3) Have antistatic carrier bags for the RAM ready. Within arms reach.

4) Touch antistatic bag with hand to bring to same potential as the computer case and you. There is sufficient conduction of your bare skin, to bring computer metal casing and you and the bag to the same potential. Pull the DIMM out of the socket, touch the inside surface of the bag, then slide the DIMM in. Grab the bag with the new RAM, touch the inside of the bag, pull the DIMM out, align keying slot with key in DIMM socket (put DIMM the right way round), then seat it. Make sure it clicks into place. The gold fingers should disappear below the line of the socket. You can even use the levers and lever it out again and re-load it, if in doubt about getting a proper click from it. Due to poor edge shaping by the manufacturer, sometimes the pressure required to seat the RAM, hurts your fingers. This is normal for "blunt" RAM sticks.

5) Plug computer in and test.

If the RAM won't seat, figure out why. DO NOT power on, if the DIMM is on an angle! Also, do not add or remove RAM with +5VSB running -- this is why we unplugged the PC, so no +5VSB is present. On an Asus motherboard, the green glowing LED on the motherboard is the warning that +5VSB is still present. Hardly any other brands, have this safety feature. By seeing how long that glow lasts, it takes at least 60 seconds from unplugging, before it is safe to pull RAM.

And one guy tried to pull my leg one day, by saying he had sawed an extra slot in the DIMM because "it didn't fit". And now the computer didn't work. Well, of course he didn't do that. Too kooky :-)

Paul

[Adrian Caspersz]

Yup, that as well, a memory controller channel limitation* - which also would come into play if you exceeded the memory channel maximum rank figure with excessive low rank DIMMs.

• That would be a situation where a computer reportedly works with single rank memory but not a higher rank.

And they described what rank of the module on the data sheet?

I think your problem is middlemen. Spec and buy direct.

[Vir Campestris]

I've never seen data last more than a minute. Even that was a shock when it happened... the bug was "The new machines aren't running the RAM test on power up".

The reason was that they built them, powered them up to check they were going to start, then unplugged them and carried them over to the soak test bench.

Where they realised the memory test had started (and we allowed you to bypass it by resetting the machine) they skipped it.

That was 256k DRAM, which should give you an idea of how long ago.

(Discs, on the other hand... I can't work out how to wipe a failed disc. May need to use a hammer)

Andy

[Paul]

Correct, same part number, different package contents.

This never used to happen in the beginning, but something changed at Kingston. The scary part would be, if they didn't know this was going on.

Companies love to set up operation flows, where they don't do quality assurance on contract manufactured materials. They simply assume every contractor lives by the details of the contract. But if you do this as a corporation, sooner or later it catches up with you.

The level of counterfeiting, varies in the types of computer hardware. Everyone knows about the problem with USB sticks on bazaar-style sales sites. Well, RAM isn't usually like that. For used RAM, you could get just about anything, but I don't usually read too many horror stories. Some people buy their RAM at "ham-fests", where the identity of the seller may be known, and that helps instill a sense of honesty. I'm not aware of a lot of commercial sealed/new DIMM products being counterfeit, even though the opportunity is there. Even the x4 chip UDIMMs they should not be making and selling, the adverts do a good job of warning buyers that they won't work in just any computer. Only a few chipsets could drive those, a full set of them. Mushkin used to have a test page, where they found just one chipset that could take a full load of them (x4 wide 16 chip single-bank DIMMs). Intel documentation only accepts x8 and x16 bit wide chips, but not x4 UDIMMs. And x8 wide chips, is the only practical choice on desktops.

Paul

[Paul]

Kingston does not sell direct. If you can locate a "Kingston store" which belongs to Kingston corporation, please advise.

Their web site will point you at disti, not their own store. You are left to fend for yourself, when locating a seller.

With Crucial it is different, and I have ordered product from their web site, which is shipped from the US. There is presumably no middle-man there. While they could drop ship, the packaging does not suggest that is happening.

Paul

[Scott]

They seemed to be out of stock and I had to order from Amazon instead. Given the reported shortage of memory, I though it best to buy when I could.

[Theo]

There has been past SD card counterfeiting:

but DIMM counterfeiting is a new one on me. Although given the prices people pay, and the likely profit to be made, I'm not entirely surprised. It may well be that someone is collecting chips from e-waste and making new DIMMs out of them.

I wonder if they are targeting particular popular lines? I typically only buy DIMMs on the used market if one in a server has failed and I want to match it - those are likely extremely uncommon part numbers (often non-retail brands). I wonder if they target mass-market brands and niches where the user might not notice (perhaps not gaming RAM, where the user is fussy about their memory)?

As ever, a trustworthy supply chain is worth a lot.

Theo

[Scott]

Thanks for all the comments. I tried to order from Crucial but they were out of stock and directed me to Amazon. Reluctantly, I ordered from Amazon for next day delivery then received an email saying it might take until 14 September. I cancelled the order.

I ordered from Mr Memory and received the modules the next day.

I installed them successfully. The computer would not work at all at first but - as with many IT issues - the solution was simple. The mains lead was not pushed in firmly enough.