CPU temp 30c at idle, 90c at full load. Wtf?!

SlapDashAsh · 29 May 2014 at 13:09

Hi,

I've recently built a new gaming PC using a Gigabyte GA-78LMT-USB3 motherboard, AMD FX-8320 cpu and Zalman CNPS8900 Quiet cooler.

I've been using Speedfan and HWmonitor to check CPU temps and something odd is happening. At idle it sits at a comfortable 30-35 degrees C, which I thought was a decent temp. But when I play a game it jumps to 90c.

I thought increasing the fan speed would help when it gets hot but the cooler only goes to 1500rpm max, which it's already hitting. And it's definitely throttling the speed as the temp rises, I opened the case and made sure of it.

Please help!

SlapDashAsh · 29 May 2014 at 13:33

Yeah. I used a pea sized blob and screwed it on pretty tight. Maybe I should start again, clean off all the paste and remount.

So, are my symptoms sounding like it's not installed correctly?

SlapDashAsh · 29 May 2014 at 13:48

Apparently the CNPS8900 Extreme goes up to 2800 RPM, but the Quiet edition only does 1500 RPM.

I did the BIOS changes you suggested but it's still only hitting 1500 RPM

I've struggled to find a decent low-form cooler that'll fit in my case (Gigabyte GZ-MA02 4-in-1). The Hydro 212 didn't fit and neither did the Corsair H55. Do you guys have any other suggestions?

Also, worth noting is the stock fan that came with the CPU gave very similar temp readings (35c->90c), but was obviously louder.

SlapDashAsh · 29 May 2014 at 15:42

I'll only be able to measure when I get home in a few hours.

So, do we think the cooler is installed correctly but just not powerful enough?
And would the 2800rpm do the trick?

SlapDashAsh · 29 May 2014 at 15:55

nkata said:
You should alter the voltages in bios if you have not done so. Auto will tend to overvolt the CPU under load. try vcore of 1.35V to start with at stock speeds.

I know nothing about this. What advantages does changing the voltage have?

SlapDashAsh · 29 May 2014 at 16:06

Correct me if I'm wrong, but it's starting to look like I'll have to buy a new case to fit a new cooler (eg. a Hydro 212)

Obviously this is less than ideal and I'd like to spend as little as possible to rectify my problem. So I don't make any more mistakes what would you guys suggest for replacement parts given my current setup...

Recap:
Chip: AMD FX-8320
Board: Gigabyte GA-78LMT-USB3
Current case: Gigabyte GZ-MA02 4-in-1
Current cooler: Zalman CNPS8900 Quiet

SlapDashAsh · 29 May 2014 at 17:36

Thanks for all the advice everyone, really appreciate it and please keep it coming.

Just because I like to live dangerously

what would happen is I threw caution to the wind and just let it run at 90c while playing games? They still run fine, but how much damage would I actually be doing?

SlapDashAsh · 29 May 2014 at 21:18

Gents, I have to admit to being a bit of an idiot.

I took the cooler off to give it a clean and re-sit it and found that I'd trapped the power cable between the CPU and the cooler plate!

Once I installed it again (PROPERLY) it's running smooth smooth smooth. 30c when idle and hitting max. 55c when running something intense like Crysis 3. Turns out a 1500rpm fan is ok for my setup. Thank goodness.

Apologies for being a numpty, and thank you all for such wonderful advice. It wasn't a waste as I now know way more about cooling than I did before. I'll be sure to pass on this new found knowledge.

SlapDashAsh · 29 May 2014 at 21:42

In my desperation on the way home I picked up a Scythe Shuriken 2B which I'm now going to pass onto a friend who's built a similar rig as me (inspired by this Eurogamer article, if you're interested - http://www.eurogamer.net/articles/digitalfoundry-2014-the-next-gen-digital-foundry-pc)

He's using the AMD FX-8350 so it'll be interesting to see how the Shuriken handles at full load.

SlapDashAsh · 30 May 2014 at 11:38

Good plan on modding the case.

It can't support 120mm unfortunately, but it can fit two 92mm fans - one exhaust and one intake. Unless I'm missing a trick here, but looking at this pic makes me think that without cutting the case up I'm stuck with the vent sizes provided.

Thinking of getting two Noctua NF-B9 then slowing down the intake fan to create the negative pressure. Am I on the right track?

SlapDashAsh · 30 May 2014 at 11:57

Doyll, your guide is actually what got me started on this fan mission

Really great advice.

nkata, I thought venting from the side (as well as the front and back) was a no no. Doesn't it disrupt that airflow?

SlapDashAsh · 30 May 2014 at 14:09

I'm going to start with the 2x 92mm, one for intake the other for exhaust and see how I get on.

Will look into the side fans though. Cheers for the help

SlapDashAsh · 30 May 2014 at 16:06

So, don't have any rear exhaust at all?

Have one for intake and the other on the side? I still have a left over stock 80mm that could remain where it's currently sitting in the rear.

SlapDashAsh · 30 May 2014 at 16:25

Ah, I see what you're saying - the PSU already has an exhaust. So leave that + the crappy stock 80mm to exhaust air, then add a 92mm intake to the side and another 92mm intake on the front.

Have I got that right?

*Edit: Given my case config the GPU is sitting about 1 inch from the bottom of the case (fans facing down). Not sure if that changes things.