My Lenovo thinkpad had 4Gb of ram in 2 sticks.
I purchased 2 sticks of 4Gb to make 8GB.

Now my laptop won't boot past Grub. I selected "recovery mode" and that also failed.

Entered the BIOS setup and that shows 8Gb of ram installed.

The OS is Debian 10, not running Gnome or KDE instead running Openbox, and has been running for about 2 weeks.

I reinstalled the original ram, and now laptop is running, just like it was.

that is the strangest thing I've ever heard of, if it was the wrong ram it would not boot at all. did you try swapping only one stick to see if that works? 1 2GB and 1 4GB then swap the other 4GB for the 4GB to see what that does?

and if that doesn't work reverse the slots that the ram is in. Is the debian 32bit or 64bit?

The Debian is 64bit (Intel i5)
The Lenovo book says it can take 8Gb (max)
I will try swapping slots, and get back to you tomorrow
thanks

does your grub have memtest86 in it?

if not do you have the Debian Install disk handy?
That has memtest86 on it


since you can boot after swapping the ram
that should get memtest86+ onto the grub menu

This is a shot in the dark, but machines can be very fussy about what type of RAM is installed and in what order it is installed in the RAM slots. Did you check the hardware manual before you purchased the RAM sticks?

Does this happen with any OS you try and run (eg. not just Linux) ?
To be clear: is this new RAM, or used?

The most likely reason I can think of is that the RAM you've added is bad. I would also run memtest86+ on it, but I would do that from a live system, not your current Debian install. Also, you don't need to actually install memtest86+ if you run it from a live system that already has it installed.

Some hardware specs of both the machine in question, and the RAM you've added that is causing the problem would be handy as well.

Also check for tiny specks of dirt or hair on the contacts, both male and female (the contacts, not the hair).

I also once had a laptop that was able to take 2 RAM sticks with 4GB each, but was designed to never recognize more than 4GB of RAM total - however, it wouldn't complain at all, boot up normally, and crash as soon as the OS tried to use more than 4GB of RAM.
Took me ages to find out what was going on.
This clearly isn't what's happening for you; just to illustrate what you're up against.

this in my opinion is the most likely cause. i've run across when all 4 sticks must match completely.

This is my other thought, wouldn't be the first time that new ram turned out to be bad.

and before someone says "but it turned on" you can have the system run with bad ram but not do any more than that.

You got that right, bad ram can sure do some strange stuff.

Yep, and not just RAM either.

Just to clarify; by "used RAM", I meant "secondhand RAM", as it's possible to buy secondhand RAM as much as anything else. As the OP doesn't say if they mean by "purchased" they mean as in: brand new or secondhand. As clearly, you would expect brand new RAM not to be faulty, as much as that does happen from time to time.

typically incompatible ram won't pass post

faulty ram might, it depends how faulty it is.

memtest86+ , test that ram.


regards compatibility, The Lenovo manuals I've seen are excellent, beautiful exploding diagrams in the step-by-step (dis)assembly.

It will have details about memory compatibility.

it may also be worth checking the timings reported by memtest86+ match those printed on the ram
I never remember the order, format is x-x-x-y where x and y are numbers ( the first 3 are usually the same )

Those timings should be set automaticity, if not config in 'bios' setup.

Yep, that's what I was thinking before myself, but forgot to mention it. Another thing is that; is the BIOS seeing the whole 8GiB of RAM when the OP adds the extra RAM? Because if so, that would be an even stronger indication again of RAM that's gone bad.