600E memory disappears

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warwound · #1 Post by **warwound** » Sat May 21, 2005 2:05 am

Morning all.

I have a Thinkpad 600E 2645-4BG and am having a sporadic problem with it detecting all installed memory modules.

It's got 32MB onboard RAM and two 64MB PC100 DIMM modules - total 160MBs of memory.

Every now and then it'll boot and only detect one of the 64MB DIMMs so i get a total of 96MBs and not 160MBs.
Going into the BIOS when it only detects one DIMM i used to see 160MBs installed RAM and 96MBs available - recently it shows 96MBs as both installed and available.

Suspecting a faulty 64MB DIMM module, i tried the Microsoft Memory Diagnostic tool.
When all memory is detected (160MBs) it reports:
Bank 0/3 DIMM 0 32MB
Bank 1/4 DIMM 1 64MB
Bank 2/5 DIMM 2 64MB
When only 96MBs of memory is detected it reports much the same except Bank 2/5 DIMM 2 is not detected.

I've swapped the DIMMs around now so each DIMM is in the other slot - since then it's failed to detect all memory once, but i didn't have time to run the diagnostic tool to see what DIMM was detected as a subsequent reboot fixed it and again all memory was detected.

I've noticed that the memory not being detected tends to occur when i use battery power - usually it runs on the AC adaptor - but it doesn't happen each time that i use battery power.
Sometimes it'll fix itself, but removing both DIMMs and disconnecting the CMOS battery for a short while always fixes it.

So i ran the Microsoft Memory Diagnostic tool and it immediately started reporting loads of memory errors - just on it's basic tests.
Looking at the errors sorted by module, every error was reported to be within the onboard 32MBs, and the 64MB modules both passed 100% ok.
A search on this forum shows it to be a (compatibility?) problem with the Microsoft tool and not necessarily valid results.
I'm trying to run MemTest86 but having problems getting a bootable ISO to work - just an endless list of '8000' scrolls down the screen and nothing much happens...
(I'll be experimenting later to get it running).

Anyone got any suggestions?
Replace CMOS battery perhaps?

Thanks.

warwound.

wa8yxm · #2 Post by **wa8yxm** » Sat May 21, 2005 5:19 am

I have to remove and re-install my memory boards from time to time as well, 600e 2645-8AU

warwound · #3 Post by **warwound** » Sat May 21, 2005 9:42 am

Do you know how new your CMOS battery is?

warwound.

farna · #4 Post by **farna** » Thu May 26, 2005 8:43 am

The CMOS battery could be the culprit, but make sure you have the latest BIOS upgrade first. Could be a BIOS glitch causing the detection problems. One other thing you can do -- clean the memory contacts. Pull the DIMMs and clean the edges with an ordinary pencil eraser. The only way to clean the sockets is with a spray contact cleaner. Spray lightly then flip the computer up to drain any residual fluid. The cleaner isn't conductive, but take the battery out and unplug the AC adapter anyway. I'd wait 10-15 minutes before powering up as well -- contact cleaner should have evaporated by then. I used to have to do things like this with older desktops that had memory recognition problems. Just the slightest bit of corrosion (even unseen) can cause signal problems. Don't touch the contacts with your fingers after cleaning -- skin oils can cause interference.

Laptop_wizard · #5 Post by **Laptop_wizard** » Fri May 27, 2005 9:12 pm

The cmos battery shoulden't be a fault. when the cmos battery is no good.
you will get and error 163 161, and a 173. First. buy some 128 Moduals.
install those. if simuler problems persist, change out your motherboard.

warwound · #6 Post by **warwound** » Sat May 28, 2005 1:56 am

Thanks for the replies.
I guess i'll try both suggestions.

I'll try cleaning the contacts with a pencil eraser later today.

And i'm hoping to replace one (or even both) of the 64MB SODIMMS with 128MB or even 256MB modules.
Can someone verify that i need PC100 single density SODIMMs?
How many chips would i expect to see on single density modules - both 128MB and 256MB - can someone post such info or a link?

Thanks again.

warwound

whizkid · #7 Post by **whizkid** » Sat May 28, 2005 12:24 pm

PC66 should work too, but PC100 has higher resell, if you ever want to.

256MB PC100 low density will have 16 chips; usually 8 on each side. I've never heard of any 128MB PC66 or PC100 chip NOT working in a 600E.

warwound · #8 Post by **warwound** » Sat May 28, 2005 12:50 pm

Many thanks Whizkid.

Been out for the afternoon taking some pictures by the local river and took my 600E.
First time i booted it up it detected just 96MBs of memory.
(Recently it's been detecting all 160MBs most of the time but that's when it's powered by the AC adaptor).
Second time i robooted (50mins later) and all 160MBs is detected.

I think either a lack of power or (more likely) a dodgy SODIMM is the problem.
I'm gonna look into replacing one or both 64MB SODIMMs as soon as my funds allow.
Presumably i don't need to use both SODIMM sockets and could just use a single 128MB or 256MB SODIMM in one socket to replace my present 2 X 64MBs?
I rather fancy a single 256MB SODIMM and the 32MBs onboard for a total of 288MBs - should be ample for the time being.

warwound.

whizkid · #9 Post by **whizkid** » Sat May 28, 2005 2:44 pm

Besides a faulty memory stick, it could also be one of the sockets. Clean the contacts and run memory in only one socket. Use something like (or exactly like) memtest86; a floppy that boots and tests RAM. It's very punishing on memory and finds almost all flaws.

Good luck shopping!

600E memory disappears

600E memory disappears

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