IBM 390X - ADDING NEW MEMORY CAN YOU HELP ?

[bunkey]

Hello, can anyone help, please ?
I have an IBM 390X P3 450MHZ. It runs on XP.
It has 128mb memory.
I want to upgrade the memory and have just bought a genuine IBM 128mb memory chip, to double the memory.
When I open the underside, I see there are two memory chips, each
64mb ( samsung ). I removed one and replaced it with my 128mb chip, and turned on. Unfortunately the computer does not fully boot, and offers several options ( on a DOS screen ? ) ; to boot in windows, which it does for a short while then returns to the same DOS ? screen , and to boot in safe mode. I quickly removed the 128 chip, replaced the 64 k chip and
rebooted, everything is back to normal !, and I am back online.
What am I doing wrong ? Do I need 2 x 128mb chips, or should I boot
up in safe mode ? How exactly do you upgrade the memory ?
I want to do this carefully as I do not have an XP cd rom !
Any advice graetfully received !
Pete

[schen]

First of all, at some point the moderators will probably move your question and this thread to the Legacy Hardware area as this area is specifically for T2x and T3x questions, so just beware that the thread might be gone soon.

That being said, replacing RAM isn't always as simple as buying genuine IBM memory. You have to be absolutely certain that you have the correct type for your particular machine as well as how much and in what distribution your machine takes. The 390x was one of the first IBM 100mhz bus machines and therefore that's PC100 SO-DIMMs (Small Outline Dual Inline Memory Modules). In fact, most after market manufacturers such as Kingston list virtually all IBM PC100 Laptop RAM as 390x model, and it was used throughout the line on the 100mhz bus machines all the way to the T22 model. So you have to be certain that the memory that you purchase is: a)RAM in good condition, b)PC100, c)a size that your machine will take. I'm almost 100% certain that the 390x will take 128Mb sticks and should take 256mb total, so that shouldn't be an issue. Therefore, it's either that your RAM is the wrong spec (you can check this out by testing them in another 100mhz, 390x or 600x, 770x/z, T20, T21, T22. If it doesn't work in any of those, your memory is either bad or the wrong spec.

Speaking of which, if the part sticker is still on your memory, it should have a PN or FRU number that can be checked to see what it is. One other thought is that, if you told the seller that your machine was a 390, but didn't say 390x, they may have shipped you PC66 which is what earlier 390 and 390e ran on.

Good luck.

[Kyocera]

My first post in the forum got moved too, welcome to the club

[bunkey]

Thankyou Schen for the advice (and your time) Very useful ! Pete

[serverbook]

the tp 390x works with 128,192,256 total ram
i have also ran quality pc133 spec no problem
the only ram i ever had issue with was a micron pc133/3.3.3
standard mac laptop issue and it gave errors etc
goes to show that ram made for macs are el cheapo b grade
incompatable pieces of junk,
theres quality ram with wide bandwidth and theres lesser quality ram with
limited bandwidth.
xxggggggggggggggggggg = quality micron,toshiba,kingston pc133rams
xxxxxxxxxxxxxxxxxxxggxx = pc133 mac crap micron ram and others.