XPS L501x Freeze/Shutdown while start\Won't start

Model: XPS L501X
OS: Win 10 professional 64 bit
RAMD: 2x 4GB DDR3-1333 SDRAM
CPU: Intel Core i7-740QM
Mobo: DELL 00YWG2
Chipset: Intel HM57 (IbexPeak-M DH)
Bios version: A08
HD: HGST HTS721010A9E630 1000GB
Video Chipset: NVIDIA GeForce GT 435M (GF108M)
Video Memory: 2048 MBytes of DDR3 SDRAM [Hynix]
Driver version: 391.35

Since September i have the following problems that randomly occurs:
-Randomly freeze while using the PC (No gaming, no overclock, it freeze while browsing or office work or vlc, normal stuff), hard reset to solve

-Everyday 8 beep at first start, then i'll do the power button+D test, and after 3 or 4 attempts it works.

-Randomly quit while starting, after Dell logo but before that windows start. Today, i've spent 20 minutes of attempt between LCD problem and Quit problem.

-Sometimes after the 8 beep start, it run but without graphic driver (low resolution and no Nvidia logo in the bottom left corner, than i restart again and everything works)

-Rarely shutdown while using it, but this is occured only 3 or 4 times in the last months while the 8 beep problem is daily and freezing is weekly.

While writing following CORE temp with only chrome open taken with Core temp:
#0-63° C (min 60 max 70)
#1-64° C (min 60 max 73)
#2-63° C (min 61 max 76)
#2-64° C (min 61 max 75)
While writing following GPU temp taken with GPU-Z
64° C  - Voltage 0,96V

New thermal paste (Noctua NT H2) over cpu, gpu changed two weeks ago.
New HD, 1 year ago
New RAM, 2 year ago.

Since is a really good machine, i'd hope to find the problem. 

Thanks to who can help
Fabrizio