Interchange RAM between laptops

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kunalzshah

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Mar 18, 2014
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A friend has a Toshiba Satellite C655 running Win7Home Premium 64Bit, which came with 2 x 2GB RAM

He also has a Toshiba Satellite Pro S850 running Win7Professional 64Bit, with 2 x 4GB RAM

RAM modules (single and both together) from the S850 works on the C655, and are also reflected in System Info.

However, RAM modules of the C655 do not work on the S850, tried all permutations and combinations. (2GB alone, 2GB+2GB, 2GB+4GB, 4GB+2GB). Reverting to the original modules of the S850, i.e. the 4GB modules, either one or both, the laptop works normally.

When RAM modules (2GB modules) from the C655 are placed into the S850, the laptop does not enter BIOS, and the power light keeps blinking.

S850 - 4GB 2Rx8 PC3 12800S-11-11-F3 - Samsung
C655 - 2GB 2Rx8 PC3 8500S- 7-10-F2 - Kingston

The wish is to interchange both RAM modules, and run the C655 with 2 x 4GB, and the S850 with 2 x 2GB. Would someone please help?

Removing battery and charger etc. have been tried, but have not helped. The CMOS battery seems to be deep inside, cannot reach it by removing covers at the bottom.

 
Solution
B
Due to the age of the older machine, it's possible Toshiba cut corners and used lower cost, higher voltage DDR-3. The standard is supposed to be 1.5V, but initially there were quite a few kits that required 1.65V to hit their rated speed. The newer i-series CPUs did not support memory above the 1.5V standard and some even ran the risk of damage with such a configuration.
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Ok. My guess it that the RAM from the older laptop is compatible speed wise with the new one, but the newer laptops RAM does not work speed wise with the old one. Motherboards only support certain speeds. It sounds like you are getting a POST error. I would put the original RAM back in and make sure it is in well. Then try to boot again. This should make the laptop re-detect the hardware.
 
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It's actually the other way around, where the old ram doesn't work in the newer laptop.
You can get new ram though: http://www.crucial.com/upgrade/Toshiba-memory/Satellite+Pro+S+Series/Satellite+Pro+S850-07E-upgrades.html
 
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The processor's memory controller in your S850 should support up to 1600 MHz 1.5V SODIMMs or 1333 MHz 1.35V SODIMMs. You might look on the 2x4GB modules and see if they are outside of this range.

It looks like the CPU in the C655 uses a MCH (Memory Controller Hub) to interface with the RAM modules, and there are two variants that are listed as compatible. One supports both DDR-2 and DDR-3, so it's possible the DDR-3 used in the older system requires a higher voltage than the newer S850's CPU can support.
 
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I tried crucial.com's RAM test on the S850, but it could not give me details... 🙁
 
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Could be the voltage thing.... Never thought of that! I guess I'll just leave it at that.
 
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Hmmmmm..... Go to the manufacturer website, then see if it lists any RAM upgrades for the laptop. I know Dell does for its products, even old ones like the precision 490.
 
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Due to the age of the older machine, it's possible Toshiba cut corners and used lower cost, higher voltage DDR-3. The standard is supposed to be 1.5V, but initially there were quite a few kits that required 1.65V to hit their rated speed. The newer i-series CPUs did not support memory above the 1.5V standard and some even ran the risk of damage with such a configuration.
 
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Solution


Whoa!!! Just realised....
Since the C655 takes the 4GB module, I have the original 2GB module + one 4GB module running on the C655. If the 4GB module requires lower power, would it ultimately blow in the C655? Or would it be OK to mix the 2GB and 4GB on the C655?
 
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It probably would, but it would be simpler to just buy 6GB of RAM. However, the controller may be able to adjust the voltage to cope. If not, you are basically OCing the RAM.
 
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No, the RAM module will not, umm, "blow," unless it's being grossly over-volted. The DDR-3 spec's also calls for the RAM modules to sustain up to ~1.9V before taking permanent damage, but they are not guaranteed to work correctly at wrong voltages.

The problem with the i-series CPUs is that they could not provide more than 1.5x volts to the RAM modules without sustaining damage to the internal memory controller of the CPU. The RAM modules didn't care. In the case of the RAM modules in the C655, if they are working without error, the voltage is likely tolerable. If the system is running as it should, and correctly sets the memory controller in accordance with the SPD data on the RAM modules, you should be running at the lowest common denominator of voltage that works for both modules.

If you're concerned about the RAM modules functioning, run a memory test, perhaps overnight, and see if you get valid DATA or errors.

MemTest86: http://www.memtest86.com/

Memtest86+: http://www.memtest.org/

Windows Memory Diagnostic: http://windows.microsoft.com/en-us/windows7/diagnosing-memory-problems-on-your-computer
 
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I ran Windows mem test and got no errors. I'll keep the 2GB + 4GB in the C655 and hope for the best! The S850 will run 4GB, and one 2GB module will remain spare.

Many thanks mate, you really helped me in understanding the problem and alleviating my fear on the RAM module blow up!!
 
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