Windows Crashes & Restarts Itself But No Message

Hi,
I have Dell workstation with following specs :
CPU : Xeon E5645
RAM : 12 GB
GPUs ; Three AMD FirePro 2460 Low Profile Cards ( To run 12 Monitors )
12 Dell Monitors ( 1920x1200 )
Windows - 7
I have been using this system for last 10 years with no problem. Reason for Win-7 is that System & Cards won't run Win-10.
Recently one Fan that sucks the air & throws inside the system was making noise but system never crashed.
I cleaned the system with a blower & took out dirt. Now it makes much less noise.
But it crashes 1 to 3 times a day & restarts itself & takes much longer 10 to 20 minutes to boot.
There is no message when restarting like graphics drivers crashed or dumping memory etc.
System is in an A/C room ( keeping temp at 86 degree F )
Can you please tell me :
(1) what is causing windows to crash &
(2) why is it taking so long boot &
(3) What should I do ?
Thank You

 

12 monitors? Wow.

Not sure what this means. Your room is at 86°F? That's pretty warm.

Please note that computer temps are stated in Celsius so that is what the tech world and experienced users and forum helpers go by. So if that temps is for the CPU, that equals 30°C and that is just fine. However, there are other components in the computer that are heat sensitive too. These include, but are not limited to, the motherboard chipset, voltage regulator devices, the GPU, system and graphics RAM and more.

If the bearings in your front fan are failing (the typical reason for increased fan noise) you may still have a heat problem. You could open the side panel and blast a desk fan in there to see if it keeps crashing. While open, make sure all fans are still spinning (and all power and data cables are securely fastened too).

Whenever I encounter unexpected shutdowns and reboots, I always suspect heat and power. You have partially addressed heat but there's still power. I always swap in a spare power supply and see what happens. That's because EVERYTHING inside the case depends on good clean, stable power. My concern in your case is Dell workstations, particularly older Dells often used proprietary parts, including proprietary power supplies. It will take careful research to make sure any replacement is compatible - if not standard ATX.

Note a failing power supply can result in system crashes that happen so quickly, the system does not have time to log an event in Event Viewer.

That said, 10 years is a long time. That means everything has aged and it is definitely time to look at upgrading to an entirely new system. You've had a good run.

In the meantime, make sure you have a good backup of any data you don't want to lose.