Max MHz DDR4 on DELL Precision 7540

On the website, it was stated: "Choose the amount of memory you need with up to 64GB of 3200MHz SuperSpeed memory or 128GB of 2666MHz SuperSpeed memory."

https://www.dell.com/en-us/shop/dell-laptops/precision-7540-mobile-workstation/spd/precision-15-7540-laptop#tabs_section

Dell's specifications indicate that your laptop supports 2666 and 3200 MHz RAM. Crucial confirms that, and here are Crucial RAM modules guaranteed compatible with your laptop. You may use up to 128 GB of RAM.

Whenever touching components or working inside a computer, wear a grounded wrist strap, also called anti-static wrist strap, ESD wrist strap, or ground bracelet. It's a cheap and sensible precaution. Rest the laptop on an anti-static mat or at least a reasonable alternative such as corrugated cardboard.

This still doesn't confirm my concerns - can I install 4x 32GB 3200 MHz?

If you try DDR4-4000 RAM, it will likely either be of lower cache latency or require XMP support -- which the system does not tolerate or have.  You could very well find the RAM defaulting to 2133 MHz in that case.

Translation:  buy from a vendor that guarantees compatibility, or understand what restocking fees might be involved if you do not.

It's working fine, but is it running at 3200MHz?

Have you checked HWiNFO64 or any other monitoring software?

I have a P7540 with 4x16gb HyperX Impact 2666MHz CL15 and at the time of the upgrade I researched a lot about the compatibility of 3200MHz modules and all I saw was that these modules worked at 2666MHz in P7540...

I installed DDR4 3200 Kingston 32GB *4 = 128GB and it halted my system running.

Kingston makes multiple types of RAM, ranging from budget ValueRAM to RAM designed for high performance gaming systems -- what is the specific part number you're using?

Note that the gaming RAM they make is aggressively timed and won't work with your system.  Neither is Value RAM likely to work.

This is the RAM they specify for your system:

https://www.kingston.com/en/memory/search/model/100443/dell-alienware-precision-mobile-workstation-7540

That sounds about right.  Xeon E2276M can support memory DDR4-2666 and LPDDR3-2133.

But from i7-9750H to Xeon E2276M to i9-9980HK, Intel ARK says all of them only support DDR4-2666,

yet the poster Karol4112's RAM works at 3200 fine.

I think there maybe some requests or limitation in running at 3200.

I have a Dell Precision 7540 with Xeon E2276M

I bought two Samsung 32G DDR4-3200 to replace the original two Samsung 32G DDR4-2666

But the RAM is still running at 2666MHz

I have tried restore BIOS setting, re-update BIOS, neither works.

OP' solution was "I didn't want to take any risks, so I purchased 4x32GB 2666MHz."

Your result is understandably within the specified lower specs.

To achieve the higher specs at 3200 MHz, it may require to meet certain conditions:

Core-i vs. Xeon

ECC vs. non-ECC

Lower capacity vs. higher capacity

Certain memory configurations.

***For example, this is the supported memory speed in an XPS 8950:

3600 MHz, 4000 MHz, 4400 MHz, 4800 MHz

The speed was changed according to different configurations:

• 8 GB, 1 x 8 GB, DDR5, 4400 MHz
• 16 GB, 2 x 8 GB, dual-channel DDR5, 4400 MHz
• 16 GB, 1 x 16 GB, DDR5, 4400 MHz
• 32 GB, 2 x 16 GB, dual-channel DDR5, 4400 MHz
• 64 GB, 4 x 16 GB, dual-channel DDR5, 4000 MHz
• 64 GB, 2 x 32 GB, dual-channel DDR5, 4400 MHz
• 128 GB, 4 x 32 GB, dual-channel DDR5, 3600 MHz