Which CPU temp monitoring is accurate?

[Built Different]

So i am in the process of overclocking my i5-4670k. Right now at 100x40 at 1.149 V Real Temp shows core temps at 75 when Gigabyte System Information Viewer shows 58 C. I heard that Real temps shows hotter temps because on Intel "cores run hotter than the actual CPU" something like that. When Mobo software/Bios uses actual CPU, no core temps. Which is the real temp?

[Astori Heichalot]

the reason why such hardware monitors show different temp results, is simply because they count ot backwards.
each chip has its own tjmax, thats when it will auto-shutdown. by predicting "how far it is" from tjmax, then realtemp could get an approximate temperature.
gigabyte sys info also work similarly. but motherboard has its own allowed cpu temp before it is auto-shutting down too, and it is different from tjmax.

1.149 vcore on 4670k will not reach 60 C especially on idle. on high processing tasks, it will also wont reach that. it will be clearer if you tell us "how high" you overclock it at.
there will be other factor such as improper cooling gel, misplaced chip, etc, but lets not go there yet.

btw 4670k tjmax is 105 C

[_I_]

if you need accuracy
http://www.newegg.com/Product/Product.aspx?Item=N82E16896268001

idle temp is meaningless
on intel 1150/1155, try to keep it under 90c

hwmonitor or core temp should be close
speedfan needs an offset to read properly

one could be reading the socket, the other could be reading the sensor on the cpu

[Chas.]

One is the core temp, the other is the socket temp.

[Built Different]

I forgot to mention that the temps I got were from Prime 95 using small FFTs.
My cooler is an Cooler Master Hyper N250. Chassis is a Thermaltake A31 Chaser with 3 intake fans and 3 exhaust fans. Ambient temp. is about 74 F

[_I_]

75c is fine for the 4670k under load
pleanty of headroom
n520 is a good quiet cooler