You should be fine as long as you have good fans in the case it will not break or become slower. oh and that particular ram has removable top heat spreader part is actually an optional part you don't actually remove whole heat spreader just top part of it slides off
Removing the heat spreaders also removes the warranty, there are other ways around the problem like moving the front 120mm cooling fan to the rear of the NH-D14.
G.SKILL Limited Warranty Policy
G.SKILL Lifetime Warranty
G.SKILL Memory and MicroSD products carry a lifetime warranty, which guarantees the products to operate, as specified by its datasheet, in the operating environment for which they were intended, for the life of the product or extent of the warranty. G.SKILL will, at its option, either repair or replace any part of its products that prove defective by reason of improper workmanship or materials. If G.SKILL is unable to repair or replace the product, G.SKILL will exchange with another product similar in functionality to the product under warranty.
G.SKILL One-Year / Two-Year / Three-Year Warranty
G.SKILL SSD and cooler products carry a one-year warranty, two- year warranty, or three-year warranty, which guarantees the products to operate, as specified by its datasheet, in the operating environment for which they were intended, for the duration of the warranty. G.SKILL SSD products are covered by this warranty for a period of two or three years from the date of original manufacture (indicated by serial number). Discontinued and out of warranty G.SKILL products are not eligible for replacement or repair.
The following cooler product carries a one-year warranty: Turbulence II
The following SSD product series carry a two-year warranty: Falcon and Falcon II.
The following SSD product series carry a three-year warranty: Sniper, Phoenix, Phoenix PRO, Phoenix EVO, and Phoenix III.
G.SKILL warranty does not apply to any G.SKILL product on which original identification information or warranty stickers have been altered, defaced, or removed. G.SKILL warranty also does not cover any product with damage that result from accident, misuse, neglect, abnormal mechanical or environmental conditions, natural disasters, unauthorized disassembly or modifications, improper installation or assembly, removal or reassembly of heat spreader, improper packaging or handling, insufficient or excessive electrical supply. G.SKILL warranty is also void under the following conditions: missing, damaged, or bent pins; missing, detached, or loose chips; damaged or missing connectors; damaged, detached, or missing casing or heat spreaders.
G.SKILL will not be liable for, and does not cover under warranty: recovery of data; installation of G.SKILL products; inspection or testing costs; installation and removal fees; and general, consequential, incidental, or special damages which include, but not limited to, loss of data and loss of profit.