Why so hot?

[BlueEyedFrog]

Hi All,

I have a 2500k running at 58c in BIOS and 49-53c in windows at idle.
Running prime95 I hit 78c, no more. Ambient room temp is 26c.
The temp seems hot - is the chip faulty?

I have an OC of 4.4Ghz, Vcore fixed at 1.3v (if I raise Vcore to 1.328 the temp exceeds 80c when running prime.)

Set up:
ASRock Z68 Extreme 3 Gen 3 MB
DDR3 2x4Gb 1600 r.jaw RAM
Synthe Mugen 2 with stock and additional 120mm fan, push/pull config.
Fractal Designs R2 case
2 x 120mm fractal designs case fans. One on rear, the other top rear.
passively cooled HD5770 GPU, stock speeds.
Seasonic 650 gold PSU

I have the fans set on the mainboard as follows:
CPU 1 = Synthe fan (4pin mb connector) set at 55c and level 1 target
CPU 2 = rear chassis fan (3 pin)
Chassis fan 1 = second PWN fan on cooler (4 pin set to same targets as CPU fan 1)
Chassis fan 3 + top rear case fan (3 pin) level 1 target (1 = slowest)

Speedstep enabled.
C3, C6, Package C disabled
PLL overvolt disabled
Core current Limit = 150

When running prime the fan speeds ramp up to what appears to be full speed (1000-1360rpm). I have the fan speed set at lowest level at idle because I want a near silent rig at idle (used as HTPC) but high fan speed is fine for me when gaming. If I set the target temps lower (45 or 50c) idle temps drop to high 40s but fan noise is unaceptable as they run constantly at full speed

I reapplied thermal paste (using 25% silver compound), size of a pea, unspread. Did not change temps. I ran the same cooler on my C2D E7300 and the fans rarely went full speed, sometime the CPU fan completely stopped.

Your thoughts...

 

[Bobnova]

At full load feel the heatsink. If it is warm your CPU is pushing your heatsink as far as it'll go and there isn't anything to be done, short of getting a new heatsink.

If it is cool or cold, you have bad contact between the CPU and the heatsink.

Given your OC, I'm guessing that the 2500k is simply too much for the heatsink, that CPU puts out more than twice the heat a C2D e7300 does at stock, and much more overclocked.

 

[BlueEyedFrog]

I'd describe the CPU cooloer as mildly warm under full load but definitely not hot. It seems cooler that my aftermarket passive GPU cooler (Accelero S1 rev2) which runs at 47c at idle.

I'll try re-seating it again. Oh joy. Otherwise, any recommendations for a replacement cooler for the synthe mugen 2?

 

[BlueEyedFrog]

By the way, thanks for your reply.

On inspection I appeared to have too much thermal paste. Re-seated the heatsink (twice) with less compound but no appreciable change in temps (using core temp), maybe 1-2 degrees cooler at idle.

Would you recommend additional case fans, different case or different cooler?

 

[Bobnova]

It's worth taking the side of the case off and aiming a house fan in it to test whether more case airflow would help. That's probably next.

If that doesn't turn anything up I think a new cooler is probably the way to go. Odds are your idle temp is highish because your fan is on speed control that favors a high idle temp.

Realistically speaking your temps aren't anything to worry about as it stands, but you aren't far from the 80c point I like to stay under. A better cooling would give you more OCing room.

 

[BlueEyedFrog]

Will try the side off as you suggest.

But if you think high 48-50c is okay for a daily idle temp then I may just settle for the current oc as I do like a quiet idling PC?

 

[Bobnova]

That's a perfectly acceptable plan, idle temps really don't matter much when you get down to it.

You could try enabling the various power saving options, my board/CPU can run power saving stuff even with a solid OC on it (like, 5.3GHz on Dry Ice...) without issues.

 

[nooster]

Have you tryed using an offset voltage and enabling power saving states?
It may give you a lower idle temp compared to set voltages.

I noticed a 3 -5 degree difference with my system after doing that.

Just a thought to try help bring those temps down a bit

 

[BlueEyedFrog]

Yes, I have speedstep enabled and I tried -.05 offset which dropped the idle voltage to about .98 but under load it went up to 1.33 and so the temp went over 81c under prime95 load.

I can't figure out how to adjust the offset to get 1.3 under load (which keeps me under the 80c).

 

[BlueEyedFrog]

Well, I found a BIG source of my heat problems; my receiver which is sitting directly above the computer. It obviously puts out a lot of heat. With the receiver off idle temps have dropped from 51c to 46.5c with max temps dropping from 78c to 71.5c.

However, with the side of the case off and a room fan pointing in I can get much lower; 39.5c at idle and 64c under load (see table).



Any suggestions as to where to from here - i.e. additional fans, if so what and where - or should I consider another case?

 

[Bobnova]

I'd put two fans in the front and one in the bottom, all intake.
That'll go a long way towards helping I think.

 

[BlueEyedFrog]

Thanks Bobnova - will give it a try...

 

[Conumdrum]

Yep, sounds like upgrading case cooling. How's your wire management?

Also room for exhaust to escape. You got the PC in any sort of enclosure?

 

[BlueEyedFrog]

Wiring is pretty good I think - all nicely tucked away and component/modular cabling from the power supply - so I only have connected what I need. I have one SSD, one 2tb HDD and two optical drives. Only card is the HD5770 (passively cooled).

I have the case in a minimalistic and very open Ikea modular shelving unit (ivar - no, I don't work for Ikea). It's about 100mm from the wall and I have about a 50mm gap between the top of the case and the shelf above. Little else is around the case (it sits on the end of the unit and not in a corner). But I think things could be improved somehow - cetainly moving the receiver away should help - possibly giving more space between the top of the case and shelf too.

Maybe I should consider taking it right off the shelving and just sitting it on the wooden floor next to it - all heat could then dissipate upwards unhindered...

I've always contemplated drilling some holes in the wall and sitting it in the room next door - no worries about noise then!

 

[BlueEyedFrog]

I'm concerned that adding fans may not achieve enough cooling, especially at the expense of noise, leading to a waste of money.

Eventually I intend to either crossfire (passively cooled) or upgrade to an HD7970, both of which will increase case heat and/or noise. My goal is to have a quiet idling rig - noise under load is a secondary concern.

Given the expense of $45 for three additional case fans I wonder if it's worth considering water cooling (e.g. Corsair H100) at $169 or upgrading the case to a Silverstone Raven 2 @ $185 (I can always flog off my existing case for $50 or so offsetting the cost of the new case to $135)?

Still can't understand why my idle temps are so high...