PC suddenly turned slow and laggy

[Flinter_cs]

I Bought my pc 2 years ago and it had been working fine unyil now. It just turned really slow over night, ive tried reinstalling windows and using someone elses hard drive. I currently have 120gb ssd that i use as my hard drive.
Sometimes when i turn on my computer it will start up, mosy of the times it turns on and turns off after around 30 seconds.

Specs: i5-4690k
8gb ram
Asus 970
120gb ssd

 

[atljsf]

what mainboard, what psu do you have there

 

[BenJaD]

Possibly a random thought. You stated that you have 120Gb SSD as your main drive. In the far not too long ago I 'knew' that keeping the OS drive at or near 50% capacity was fundamental when dealing with a multiple simultaneous processing OS.
I have dealt with machines that do the turn on - turn off behavior. Most of those issues were identified as high CPU temps that were causing self preservation action by the processor.

 

[Flinter_cs]

Possibly a random thought. You stated that you have 120Gb SSD as your main drive. In the far not too long ago I 'knew' that keeping the OS drive at or near 50% capacity was fundamental when dealing with a multiple simultaneous processing OS.
I have dealt with machines that do the turn on - turn off behavior. Most of those issues were identified as high CPU temps that were causing self preservation action by the processor.

Yeah about that i forgot to say that when i went into the bios it said the cpu was at 90 degrees even though i didnt start the pc for maybe 4 days.

 

[Flinter_cs]

what mainboard, what psu do you have there

My psu is 650 something i dont know the brand and the motherboard is a msi z87 MPOWER

 

[atljsf]

650 something is important

the cpu, what heatsink do you have in it, how long you haven't changed the thermal pasted in the cpu

 

[Flinter_cs]

I have a water cooler not sure what it is but ive never had a problem with it. I never changed the paste so that may be why

 

[BenJaD]

Possibly a random thought. You stated that you have 120Gb SSD as your main drive. In the far not too long ago I 'knew' that keeping the OS drive at or near 50% capacity was fundamental when dealing with a multiple simultaneous processing OS.
I have dealt with machines that do the turn on - turn off behavior. Most of those issues were identified as high CPU temps that were causing self preservation action by the processor.

Yeah about that i forgot to say that when i went into the bios it said the cpu was at 90 degrees even though i didnt start the pc for maybe 4 days.

The 90 degree CPU temp at startup after being at rest for an extended period is likely to be the problem with the start/stop behavior. If you are getting that elevated temp at startup - any load on the CPU will likely push the CPU into shutdown. Take a close look at your CPU cooler - ensure that all the fittings are snug and secure; they may have loosened overtime. If that is not the case - then do not run the machine until you have replaced the CPU cooler - make sure that you use a cleaner to remove any old thermal grease from the CPU - it wouldn't hurt to do the same thing with the contact area on the new cooler either. Be liberal with the new thermal paste - but not extravagant. Arctic Silver has an excellent how to visual on their site.
When you have the CPU opening in the sub 50 degree range - your other issue may go away. Don't hold your breath!