Baffled: moving memory sticks from one laptop to another halves it

[urlwolf]

Donnor: hp elitebook 8540w (16gb DDR3)
Host: hp elitebook 8570p

Both are i7.

Both the BIOS and the OS (win 7) of the 8570p say I have 8 gigs. If I remove one stick, it sees 4gb.

Does anyone know why?
Thanks in advance.

[mouser]

I'm not following the description of the situation.

[40hz]

It sounds like one of the RAM sticks (or a memory slot) is defective.

Did you try pulling all the RAM out, then installing each stick individually to see if there's any difference between the two?

If not, try different slots for the  RAM sticks in the 8570. See if that brings you up to expected amount of RAM.

 

[Ath]

Does it only see 1 side of the double-sided stick ?

[urlwolf]

Each stick is seen as 4gb, alone.
@Ath, maybe. What could be done?

@mouser, same sticks show as different sizes in different laptops. Perfectly functional memory otherwise, uptime in days.

[Renegade]

It sounds like one of the RAM sticks (or a memory slot) is defective.

-40hz (August 24, 2013, 06:40 AM)

Well, maybe not... Just try buying new laptops until it works. (Just kidding! No. I'm not kidding. Support the economy. Just kidding! No, I didn't mean to say "don't support the economy"... oh, nevermind...)

Did you try pulling all the RAM out, then installing each stick individually to see if there's any difference between the two?

If not, try different slots for the  RAM sticks in the 8570. See if that brings you up to expected amount of RAM.

-40hz (August 24, 2013, 06:40 AM)

I've seen that work. And commonly with USB devices and ports.

[Ath]

@Ath, maybe. What could be done?

-urlwolf (August 24, 2013, 07:34 AM)

Nothing but replace the mainboard, or use other brand/type of memory card.

[urlwolf]

Will try swapping the sticks, thanks.

[mwb1100]

Make sure that the BIOS of the 8570p has the latest update.

[urlwolf]

It does.

[Shades]

Is the memory controller on the host even capable of addressing the amount of memory you put in?

Has the donor 8GByte of RAM soldered on the mainboard and are the the extra RAM slots not filled with 4GByte sticks? So that the donor system came to a total of 16GByte, but that you are just transferring 8GByte of RAM from the donor to the host?

Does the donor memory require more juice than the host can deliver? Are you moving around EEC memory modules?

Take a good look at brand/model,type number from the modules you are moving and take look on the internet for specs (latency, speed, timing settings) and check if the receiving memory controller is able to work with these specs.

Sometimes it really just the combination of RAM sticks that create havoc on a memory controller while working fine separately.

[Vurbal]

Has the donor 8GByte of RAM soldered on the mainboard and are the the extra RAM slots not filled with 4GByte sticks? So that the donor system came to a total of 16GByte, but that you are just transferring 8GByte of RAM from the donor to the host?

-Shades (August 24, 2013, 04:19 PM)

A quick look at the service manual for the 8540W seems to suggest there could be another memory bank under the keyboard with 2 additional slots.

Computers that use the system board with spare part number 595764-001 or 630293-001 have two
memory slots.

Computers that use the system board with spare part number 595765-001 or 630294-001 have four
memory slots. On these computers, in both the expansion memory slots (on the bottom of the
computer) and the primary memory slots (under the keyboard), slot 2 cannot be populated if slot 1 is
not populated.

[40hz]

^The two slot 8540w dual-core maxes out at 8GB.

The four slot 8540w quad-core maxes out at 32GB.

So since he's reporting 16 GB and an i7 chip it must be a quad-core 4-slot model - which could be configured in one of the three following ways to equal 16GB.

• 4GBx4
• 8GB+4GB+4GB
• 8GBx2

The 8GBx2 configuration isn't eligible since he mentions two memory sticks in the machine he transferred RAM to. So that leaves only the first two RAM configurations.

Looks like he moved two 4GB sticks to the 8570p (which only has two available slots) and left either two 4GB - or one 8GB - stick behind in the 8540w.

That would leave both machines reporting 8 GB  - and explain why removing one stick drops total RAM down to 4GB in the 8570p.

That's the easiest explanation that fits the given data.

[urlwolf]

40hz won the price.
I didn't remember this was the case... it did have some sticks under the keyboard, yes! Now we all know

Thanks!