Laptop won't start after cleaning and applying new thermal paste

Great!!! Congratulations.

Please mark this treat as solved.

but now it maxes out at 75c.

That's still too hot for me.

Depending on the TIM you used, it may come down a few degrees as it cures over the next couple days. But if doesn't you still have problems. Maybe your fan is not spinning properly. Or something is blocking properly air flow.

If you compare a desktop heat sink with the one used on a laptop you understand why the temperatures on a a laptop are high.
All old laptops work with high temperatures.

If you compare a desktop heat sink with the one used on a laptop you understand why the temperatures on a a laptop are high.

Of course notebooks run inherently warmer. But 75°C is still too warm.

And old has nothing to do with it. In fact newer laptops tend to be more heat sensitive simply because they are more powerful but at the same time, thinner. Notebook makers can pack in the power but not the cooling of a PC. But again, 75°C is still too warm. It should not hurt anything IF all the thermal protection features are working properly - but it means the system will throttle back in performance sooner and more frequently because of heat.

@ OverEight - when you say "high load", what is actually running and what is the CPU utilization at that time? What is the temp when idle?

I've seen Core 2 duo laptops (Sony) where CPU were running at 85ºC and GPU (NVidia) above 95ºC.
Old CPUs like Core 2 duo were 45nm and new Skylake are 14nm thick. So for the same processing, the old generates a lot more energy waste (heat).
From Intel: (I5 6600)
Thermal Trip: The processor protects itself from catastrophic overheating by use of an internal thermal sensor. This sensor is set well above the normal operating temperature to ensure that there are no false trips. The processor will stop all execution when the junction temperature exceeds approximately 130 °C. This is signaled to the system by the THERMTRIP# pin.

Junction temperature it's a lot more hot than case temperature, but as you can see, 75ºC it's normal, specially in laptops.

Megahertz07 said:

I've seen Core 2 duo laptops (Sony) where CPU were running at 85ºC and GPU (NVidia) above 95ºC.
Old CPUs like Core 2 duo were 45nm and new Skylake are 14nm thick. So for the same processing, the old generates a lot more energy waste (heat).
From Intel: (I5 6600)
Thermal Trip: The processor protects itself from catastrophic overheating by use of an internal thermal sensor. This sensor is set well above the normal operating temperature to ensure that there are no false trips. The processor will stop all execution when the junction temperature exceeds approximately 130 °C. This is signaled to the system by the THERMTRIP# pin.

Junction temperature it's a lot more hot than case temperature, but as you can see, 75ºC it's normal, specially in laptops.

This is all a bunch of BS! Why are you referencing CPUs that don't apply here? That just obfuscates this issue. The OP has a Core i5-2450M. That is NOT a Core 2 Duo, nor is it an i5 6600. To pretend the characteristics of one CPU applies to all is just silly. Even the two you referenced are totally different and have no bearing in the OPs issue.

And BTW, I have an i5 6600 in this system. NO WAY can it tolerate 130°C.

75°C is still a "safe" level for the OP's processor, but no way is that "normal" - especially when we don't know yet what "high load" means in this case, or what the idle temps are.

[QUOTE=Itaregid]

@ OverEight - when you say "high load", what is actually running and what is the CPU utilization at that time? What is the temp when idle?

High-load would be 80%+ CPU load.

Under slight/idle load, check the link I posted a link to Imgur on my previous post.

To be fair it wasn't even this cool when I first got it, so basically this is the best I can get it. You can't overcome bad laptop case design, and this laptop is exactly that.

Okay, 52-53°C at idle is not bad, depending on your ambient (room) temps.

You can't overcome bad laptop case design, and this laptop is exactly that.

I don't think it fair to call it a bad laptop design. Heat issues are inherent in all laptops. I would call it bad or misleading marketing for the entire laptop industry. IMO, there is no such thing as a good "gaming laptop" or a "desktop replacement" laptop.

The problem is, users are demanding more power, but at the same time, they are also demanding thinner and lighter laptops as well. PC makers can pack the power of a PC into a tiny laptop case, but not the cooling. Consider even full PC cases are challenged to keep a gaming PC properly cooled and a PC case supports many large (wide and thick) fans through many square inches of vents.

FTR, I have a Toshiba i5 as well and it typically runs about 46 - 48° with normal use - normal being doing tasks like surfing the Internet, email, or submitting forum posts. It jumps to 65 - 68° when pushed. When it climbs higher, I know it is time to clean out the dust and/or put it on a cooler pad.

You did not state the model number of your Toshiba so we don't know the size. Mine has a 16.5 inch monitor so fortunately it supports a pretty wide fan. Though again, because laptops are thin, that fan is not very thick so it cannot grab lots of air while spinning. If I am going to task it for long periods of time, I use my laptop cooling pad - which I recommend you check out. Make sure you get one that has an external power source so it does not put even greater demand on the notebook it is trying to cool.