I finally got my PC build put together and am going to run Prime95 (small fft) the rest of the night to see if it's stable. I initially had my i5-2500k OC'ed to 4.6GHz, but noticed that ~30 minutes into the stress test Real Temps was getting upper temperature readings of 75C on my CPU cores and Package temperature of 78C. Distance to TJ Max also dipped below 30 (which I read was the threshold you don't want to cross). So right now I lowered my OC to 4.2GHz and am getting core CPU at 70C and below and Package temperature at 70C. Distance to TJ Max is barely hovering above 30 and dips under it every once in a while. Is this the sweet spot for my system? Would it be okay to bump back up to 4.6GHz, or should I not risk it?

[edit] After some time Real Temps is showing average CPU core temps of 59/65/67/61. It's averaging around 5C lower than before, which I read would happen (due to the thermal paste needing to get warm so it can spread out better). So as long as my rig stays in this range for the rest of the night, I should be okay, right?

Anything over 80C is getting into the danger zone, 60C is a good sweet spot. 70C should be fine as long as it's not constantly at that temperature. If you're still using the stock cooler, you should pick up an aftermarket cooler if you plan on overclocking.

Actually, if you are using an aftermarket cooler, what kind of voltages are you running to get to 4.6?

@WilltheMagicAsian said:

Anything over 80C is getting into the danger zone, 60C is a good sweet spot. 70C should be fine as long as it's not constantly at that temperature. If you're still using the stock cooler, you should pick up an after market heatsink if you plan on overclocking.

This is a pretty good idea of what you should look out for (especially the after market heatsink part, its a must if you are overclocking.. Also keep in mind that PRIME 95 puts your CPU under almost completely unrealistic stress, so the temps it produces will be higher then say if you're playing a game or even doing rendering.

Shit, I've only got mine at 3.3-GHz... I should at least bump it up to 4.0.

when i was overclocking my 2600k  to 4.4ghz it hovered between 65 - 70 celsius at full load when i was stress testing...  how much voltage are you putting on the CPU?  your temps seem pretty high.

Seeing much of an improvement from stock to OCed?

Yeah, I'm using an aftermarket cooler: Noctua U9B SE2. It only has two 92mm fans in push-pull configuration. I would have gone for 120mm fan aircooler but my mATX case is pretty narrow and I couldn't find one that would allow me to close the side panel.

I don't remember what voltage the CPU was running at when it was OCed to 4.6GHz. I have a Asus Maximus IV Gene-Z motherboard, and it's BIOS basically has a "Overclocking For Dummies" feature. I literally opened a drop-down menu and selected 4.6GHz. At 4.2GHz though the voltage on CPU-Z reads 1.304V.

This is my first PC build too, and when researching my mobo & CPU combination I found a lot of people who were hitting 4.6GHz @ mid-60C using only aircoolers. I'm kinda trying to figure out if my ~75C results were due to me having a smaller aircooler, me incorrectly installing the CPU cooler, or a combination of both.

@Barrock said:

Seeing much of an improvement from stock to OCed?

I didn't get any results from doing stock. Going off of memory, here are my Cinebench results between 4.6GHz and 4.2GHz:

• OpenGL Score: 4.6GHz= ~67 / 4.2GHz= ~61
• CPU Score: 4.6GHz= ~7.5 / 4.2GHz = ~6.0

What motherboard do you have?

@Barrock said:

What motherboard do you have?

Asus Maximus IV Gene-Z/Gen3

Also, after some time Real Temps is showing average CPU core temps of 59/65/67/61. It's averaging around 5C lower than before, which I read would happen (due to the thermal paste needing to get warm so it can spread out better). So as long as my rig stays in this range for the rest of the night, I should be okay, right?

@Andorski: Yep.

I just tried to OC to 4.5. Blue screen as soon as I booted up. Damn.

Your heatsink is fine. Make sure you didn't put too much/not enough of the thermal paste on when you bolted it to the CPU (a pea-sized amount is all you need), and make sure you case has good air flow. Also, what is the ambient temperature in the room? Having lower ambient temps makes a huge difference as well.

It's also possible that the motherboard runs a higher-than-needed voltage setting to guarantee stability. Your best bet is to not use the EZ-mode, 1-click overclock settings, and manually tweak the options instead. This takes a lot of trial and error, but you'll end up with a better, more long term overclock as a result. The best way to start is to run the default voltages, and slowly increase the clock speeds (like, say 200Mhz at a time on the CPU), run stability tests at each increment, and repeat the process until it becomes unstable. Only at that point should you increase processor voltages.