i7-8700K Temperature Spikes?

[Kevsta]

I just overclocked my 8700K today to 4.9 GHz, could hit 5 GHz @ 1.35V but I lowered it a bit since I saw the temperatures spiking for some reason in HW Monitor. While at idle, I'm sitting at around 41 C and suddenly for a split second, it hits 60-70C then goes back down. Is that normal for this CPU?

If it helps, I'm using Thermaltake TG-3 that's been used, on the shelf for about...3 1/2 years? Would that be the cause? It looks fine during application, not too liquid-y.

Specs:
i7-8700K @ 4.9 GHz & 1.32V
ASUS ROG Strix Z370-f
Corsair H80i v2
EVGA GTX 1080 Ti FTW3
Corsair Vengeance 2 x 8 GB @ 3000 MHz
EVGA SuperNOVA 750 G3

Any help is appreciated!

 

[cookiemania66]

things like these can happens mostly due to short intense usage (windows or other programms).

 

[Lutfij]

Those are some really high voltages. You should be able to hit that number at 1.25'ish. I'm not a fan of using Thermal Paste like Thermaltake's TG-3 since they have low shelf life and aren't the best out there. I personally use Arctic Cooling's MX-2.

Drop down the voltages and test for stability then look at your temps. Also make sure you're on the latest BIOS update for your motherboard.

 

[vMax]

The idle temps are way to high...As Lutfij has said, try to drop vcore down but I would also check you Cooler to make sure it is on properly. You should be idling in the very low 30's...

 

[logikabg2004]

The voltage is really tricky and you have to watch out.
1.It doesn't have the same safety measures as a gpu , so you can fry it a lot easier if you do it inc orectly.
2.The heat can rise even with a tiny overcloak,depends on cooler,thermal paste,fan speed.
Your motherboard is made for CPU overcloakimg,your processor is a coffee lake CPU , so it is made for big overcloacking , and it is the newest CPU model(newer than skylale ,kaby lake ,etc) 60-70degrees is pretty safe , CPUs and GPUs can be maxed out to about 90-95 degrees limit , but they can survive a lot higher temperatures than that.
The idle temperature is probably (I assume), that there is somekind of programm running, it might not be shown on the taskbar but you can check in task manager.
Happy overcloacking

 

[Kevsta]

Thanks for everyone's input. I'm going to drop the voltages and play around with it some more. I'm also assuming that my thermal paste has gone bad/isn't as effective anymore? I'm looking to order some Arctic Silver MX-4, which I would assume has a decent shelf life? I don't build many computers, so I would hate to just let a tube of paste go to waste (sorry for the rhyme).