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Precision 7740 memory configurations
I am looking to understand if configurations not mentioned in the manual are allowed.
For instance, can I have 2x4GB in the primary slots (under the keyboard) and then add 2x16GB in the secondary slots (which are more easily accessible from the bottom). This would be 40GB total which is not explicitly stated in the documentation.
If I were to do this, I would make sure the timing spec matches.such as 2666.
ibmarc
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105 Posts
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November 18th, 2020 15:00
Modern RAM controllers allow mixtures of RAM to work under a variety of conditions. The downfall to this is RAM has a maximum speed it can operate when everything is identical. When everything is not identical RAM runs slower. If you want the best performance at the cheapest cost, figure out which slot the 8 GB module you have now is in, B or D (you can do that with the above command), and then install 1 of these modules, under the back cover in A (if other in B) or C (if in D).
ibmarc
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November 17th, 2020 14:00
I don’t think Dell sells the Precision 7740 with 4GB RAM modules. Probably the best thing to do is see what’s there. Open an Admin Command Prompt and issue the command sequence:
wmic memorychip get manufacturer, capacity, partnumber, speed, memorytype, devicelocator, formfactor >c:\ramdata.txt
Post the file ramdata.txt contents (Copy & Paste) in your reply.
catonyx
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November 17th, 2020 20:00
I can buy this with 1x8GB (or with 2x16GB). But I was hoping to add more memory later hopefully cheaper. I still wonder if I will have to "throw away" the ram or will the hardware deal with it. :).
Is it a necessity to have matching sizes in various slots?
McAlfso
9 Posts
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January 28th, 2023 14:00
For what it is worth - I tried to install the following RAM -- and failed
G.SKILL Ripjaws Series 64GB (2 x 32GB) 260-Pin DDR4 SO-DIMM DDR4 3200 (PC4 25600) Laptop Memory Model F4-3200C22D-64GRS
Laptop wont boot up and indicated "Invalid memory installed". I tried to install all possible RAM module configs - All 2 pairs (4x32 = 128GB total), each module individually (32GB) and each pair (2x64GB) individually . All attempts failed. It's somewhat unlikely that I had 4 defect RAM modules. I installed single and double modules as specified in setup/spec guide.
The mem spec does meet the memory spec for the 7740 laptop. However, the guide does not mention CAS Latency requirements.
The laptop spec states:
Memory options
● 8 GB - 1 x 8 GB
● 16 GB - 1 x 16 GB
● 16 GB - 2 x 8 GB
● 32 GB - 1 x 32 GB
● 32 GB - 2 x 16 GB
● 32 GB - 4 x 8 GB
● 64 GB - 4 x 16 GB
● 64 GB - 2 x 32 GB
● 128 GB - 4 x 32 GB
Type: DDR4 SDRAM ECC and Non-ECC memory
Speed:
● 2666 MHz
● 3200 MHz
Beemray
14 Posts
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January 28th, 2023 20:00
Yes, you can add RAM later, but it will operate on the lowest hz. Say you got 2x16GB operating at 3200 hz and 2×8 operating at 2666 hz, all of your RAM would operate at 2666 hz.
B