cancel
Showing results for 
Search instead for 
Did you mean: 
Reply
mjdl
Token Ring
Posts: 161
Registered: ‎06-10-2009
Location: Toronto, Canada
Views: 1,364
Message 1 of 5

Mix two different pairs of memory sticks in a W520?

I have 2 x 4GB sticks of G.SKill F3-8500CL7D-8GBSQ DDR3-1066 PC3-8500 CL7-7-7-20 SO-DIMM.

 

They worked perfectly as the only memory sticks in a W500, but I'd like to install them in addition to the 2 x 4GB Lenovo memory sticks that came with the W520.

 

Is this going to work and be stable at all? After reading the W520  specs, I'm still uncertain about the memory speeds of the two different sets of sticks and if that is a real compatibility issue. I don't know enough about memory specs.

Community SeniorMod
Community SeniorMod
Posts: 3,329
Registered: ‎12-01-2007
Location: US
Views: 1,352
Message 2 of 5

Re: Mix two different pairs of memory sticks in a W520?

Hello,


Very generally speaking, when you install different memory modules, they will all operate at the highest speed and timings commonly available to all installed memory modules.  So, if the W520 hypothetically has PC3-8500 memory installed, it would operate at that speed, but if the installed memory has slower timings (say CL8-8-8-8-21), the G.Skill memory will likely be run with the slower timings those instead of its default faster ones.

 

In practice, you can check the memory timings of the instdalled RAM using something like CPU-Z, and then check with G.Skill to maker sure the F3-8500CL7D-8GBSQ kit will work with those timings, and then plug them in and you'll be good to go.

 

Even if the system boots up and works fine,  I would still suggest running a program like MemTest86 overnight in order to test the RAM to make sure it is all working properly together.

 

Regards,

 

Aryeh Goretsky

 



I am a volunteer and neither a Lenovo nor a Microsoft employee.

L380 YogaP72 (20MB-*)P50 (20EN-*)S230u (3347-4HU)T23 (2648-LU7)T42 (2378-R4U)T43p (2678-H7U)T61p (6459-CTO)W510 (4318-CTO)W530 (2441-4R3)W530 (2441-4R3)X100e (3508-CTO)X120e (0596-CTO)X220 (4286-CTO)X250 (20CM-*)Yoga 370

  Communities:   English    Deutsche    Español    Português    Русскоязычное    Česká    Slovenská    Українська   Język Polski    Moto English

mjdl
Token Ring
Posts: 161
Registered: ‎06-10-2009
Location: Toronto, Canada
Views: 1,321
Message 3 of 5

Re: Mix two different pairs of memory sticks in a W520?

Thanks for the advice, particularly re. CPU-Z and testing with Memtest-86! I installed CPU-Z, and the current RAM sticks have this configuration:

 

    Memory type        DDR3
    Module format        SO-DIMM
    Manufacturer (ID)    Samsung (CE00000000000000)
    Size            4096 MBytes
    Max bandwidth        PC3-10700 (667 MHz)
    Part number        M471B5273DH0-CH9  
    Serial number        664F78D8
    Manufacturing date    Week 40/Year 11
    Number of banks        8
    Nominal Voltage        1.50 Volts
    EPP            no
    XMP            no
    AMP            no
JEDEC timings table        CL-tRCD-tRP-tRAS-tRC @ frequency
    JEDEC #1        5.0-5-5-14-19 @ 380 MHz
    JEDEC #2        6.0-6-6-17-23 @ 457 MHz
    JEDEC #3        7.0-7-7-20-27 @ 533 MHz
    JEDEC #4        8.0-8-8-22-30 @ 609 MHz
    JEDEC #5        9.0-9-9-24-33 @ 666 MHz

 

and they are being run as follows:

 

Memory Type            DDR3
Memory Size            8 GBytes
Channels            Dual
Memory Frequency        655.3 MHz (1:5)
CAS# latency (CL)        9.0
RAS# to CAS# delay (tRCD)    9
RAS# Precharge (tRP)        9
Cycle Time (tRAS)        24
Command Rate (CR)        1T

 

Am I right in thinking that after installing the slower G.Skill sticks, the whole memory system would run at the nominal JEDEC #3 rates, i.e. around 533 MHz and thus at 80% of the current rate? But in practice, would I ever notice a difference? Very few programs are exclusively memory bus speede limited.

 

I shall have to experiment.

Community SeniorMod
Community SeniorMod
Posts: 9,381
Registered: ‎01-01-2010
Location: US
Views: 1,310
Message 4 of 5

Re: Mix two different pairs of memory sticks in a W520?

I doubt you would ever notice any difference.

Rich


I do not respond to requests for private, one-on-one help. Your questions should be posted in the appropriate forum where they may help others as well.

If a response answers your question, please mark it as the accepted solution.

I am not an employee or agent of Lenovo.
mjdl
Token Ring
Posts: 161
Registered: ‎06-10-2009
Location: Toronto, Canada
Views: 1,279
Message 5 of 5

Re: Mix two different pairs of memory sticks in a W520?

Quite right, there's really no perceptible diffrence in performance.

 

I assigned the faster pair of sticks to slots A and the slower to slots B. I'm assuming that any memory access interleaving occurs across the pairs in either slot A or slot B, not between slot A and B.

 

In any case, the result is that the four sticks use the JEDEC #3 speed and timings, according to CPU-Z. Memory testing showed no sudden problems or crashes.

 

Thanks for all of your help on this matter!

Check out current deals!


Shop current deals

Top Kudoed Authors