A Core i7 CPU Cooling Question

Last year, I went out and bought a Core i7 920 CPU, and a neat little Shuttle case to slap it in. Save for some early troubles with the RAM, everything's been pretty much gravy. But I'm wondering, you see, I noticed recently that my CPU was humming along at low loads around 55C. Being that I actually had a previous processor go south on me due to overheating, I did some research, and was pleased to find out that 55C isn't way out of bounds for a i7, but it's still a bit higher than where i'd prefer, and what some others seem to report (<50C).

I have become concerned, primarily, because i've noticed it spiking up recently into the 75C+ area when doing even 30-40% loads, which obviously, makes me a sad panda.

Two things though. I've pretty much been keeping a casual eye on my CPU temp since I got this machine, and its lows when idling and websurfing (around 55C) have always been such. And I do my damndest to keep it clean, even though the room i'm in is a dust disaster (not to mention the ambient temperature isn't exactly chilly). I recently gave her a CPU stress test with HeavyLoad, and while it certainly went high (85C) it pretty much held there at 100% of CPU usage.

Really, i'm just wondering if I should be concerned? I haven't had any real troubles to speak of with the machine, other than ones of my own unfortunate doing. Should I just accept things as they are, or am I setting myself up for (another) catastrophic failure?

but it's still a bit higher than where i'd prefer, and what some others seem to report (<50C).

Are these other people reporting these temperatures also using the same tiny little case?

If they are, it might be worth taking off the cooler, applying some new higher quality thermal paste, and trying your cooler install again. But there's other things to consider, like where the case sits, the ambient temperature of the room it's in, and any number of other things.

I built a Shuttle for my sister as a wedding gift a while back (they had a tiny apartment and only a small desk for the ancient dell they had) with an old first gen Core2 chip I had spare at the time. Idle temperatures were about 6C higher in that case than they were in the mid tower I had the same chip in before, and load temps were roughly 10c higher. I don't know if Shuttle's changed their cooler designs since then though, and it's a different chip so it's not all that relatable.

Just saying... cramming high end hardware into a case the size of a small shoebox has some inherent flaws. Cooling is one of them.

Ok, I recently became a semi-expert in this area, so I'll share what I learned. When you say you got your i7 last year, was it early last year, or late? reason for asking is that the i7's have the C0 stepping (older) and the D0 stepping (newer). The C0 which is what I have, generally speaking runs hotter than the D0. So when you see other people's reported temps, keep that in mind for a start.

Next up is the luck of the draw. CPU's are like fingerprints, each one is different, even if they're from the same build, stepping, etc. Some might get a C0 that runs in the low 40's, others might get a mid 50's. Low to mid 50's idle is not uncommon for an i7, esp a C0.

Thin_J is dead on regarding your case. I'd be willing to be that's a large part of your problem. Big airflow through a case will make a big difference. Imagine putting a space heater in a bedroom with no fans, no windows and a closed door. The ambient temp of the room will build, and build quickly. The heat can only escape through the small slits around the door. So heat is building faster than it escapes, so the temp rises. If you have the same space heater, same room, but open 3 windows, and open the door, and put a big floor fan between the windows and door, cooler air can be brought in while the hot air is pushed out. Heat is escaping faster than it is building up.

My i7-920 is a C0 stepping, and was put in a large tower case, but the case was 7 years old and had poor ventilation. My internal component cables were shoddily done and the cables created a big mess that impeded air flow. my i7 was idling at 55 to 58c. I live in Florida, and ambient temp is higher here, which brings me to the point that where you live and the season also play no small factor in cpu temps!

Other factors are the quality and proper application of thermal compound, and the proper affixing of your heatsink/fan to the CPU. If you dissamble your HSF, remove it, and take a look at your cpu, you'll see markings as to how well your HSF is making contact with the CPU. if you see soft spots/gaps, you're probably not making full contact. Also note that too much thermal compound can actually impede proper heat transfer from the CPU.

One of, if not THE biggest factor in CPU temp is the voltage the CPU is running at. You can overclock an i7-920 to say, 3.2ghz, and if the voltage is the same as what your stock voltage was, you're not likely to see much, if any, increase in cpu temp. Many i7-920's will run at a much lower voltage than your BIOS may be 'auto' assigning it. For months I had mine on 1.25 volts because my BIOS had not been updated, and it was choosing a much higher than needed voltage. In my recent learning experience, I found that my CPU would run at 1.1v easily. Some 920's will even go to 1.04. When I updated my BIOS, it even began to properly suggest 1.1v.

So, what I did was to purchase a new case, the awesome CoolerMaster HAF932 (HAF = high air flow). This uber modern case features 4 GIANT fans - three 240 mm intake, and one 180mm (i think) exhaust). The case is huge, and roomy, and also has excellent cable management, allowing me to get all my cables hidden and tucked away and no longer impeding air flow. Btw, larger fans actually mean softer noise. The bigger the fan, the quieter it will be, generally.

Next thing was that I bought a decent cooler. The CoolerMaster V8. It's a MAMMOTH cooler though, and will in no way fit in your case (hehe, it's probably bigger than your case).

Then I 'lapped' my CPU, which is easy to do, and drops cpu temps by 3 to 5c (more info on lapping upon request). Lapping plays into two things. 1. removing a thin layer of tin over the cpu's copper inner layer (copper transfers heat better), and most importantly 2. the flatness of the cpu surface. the flatter the better for matching up evenly to the heatsink surface. Some heatsink surfaces need to be lapped as well.

Then I applied ArcticSilver 5, (properly per their instructions).

New result: all 4 cores running between 38 and 42c. On chilly days (yes, we have those in FL), I can see all 4 cores drop into the 30's.

The bad news is you're not going to achieve this in a mini-case. The good news is that the i7-920 can run all day long, 7 days a week at 85C. The upper limit on that chip is something like 100 to 105c.

edit: forgot to ask, what are you using to measure your cpu temps?

Jeff-66: Interesting to hear your exploits into CPU cooling. I'm running a 920 at 3.2 w/ turbo mode on and getting average temps with low load around 40-50 C at idle to low loads. Under full load (using Prime 95) I'll get it up to 80-85 or so. I've got one of those closed circuit cheapo water coolers (with the 120mm fan I think) on mine. While it isn't all that great, it does work and it is quiet enough. I haven't been all that concerned about it running that hot. I can't really overclock it past 3.2 because I'm using 1333 Mhz memory. I'm happy enough with the slight overclock and reasonable temps. I really would like it to be running in the 30's like yours though. I just use realtemp to measure core temps. It's addicting though. I'm always glancing down at the system tray checking my temps... That darn obsessive compulsion.

Prederick: You're CPU temp is probably fine, although I know how you feel getting paranoid with your temps. Mine seems to be running a bit below yours at idle speeds, but about the same at load. It's easy to obsess over.

tuffalobuffalo wrote:

Jeff-66: Interesting to hear your exploits into CPU cooling. I'm running a 920 at 3.2 w/ turbo mode on and getting average temps with low load around 40-50 C at idle to low loads. Under full load (using Prime 95) I'll get it up to 80-85 or so. I've got one of those closed circuit cheapo water coolers (with the 120mm fan I think) on mine. While it isn't all that great, it does work and it is quiet enough. I haven't been all that concerned about it running that hot. I can't really overclock it past 3.2 because I'm using 1333 Mhz memory. I'm happy enough with the slight overclock and reasonable temps. I really would like it to be running in the 30's like yours though. I just use realtemp to measure core temps. It's addicting though. I'm always glancing down at the system tray checking my temps... That darn obsessive compulsion.

Prederick: You're CPU temp is probably fine, although I know how you feel getting paranoid with your temps. Mine seems to be running a bit below yours at idle speeds, but about the same at load. It's easy to obsess over.

Yes, I was going to say, about the only thing you should be measuring temps (IMO) with is RealTemp.

3.2ghz is not a bad OC for a 920. It's a 20% increase, esp if you can pull it off w/Turbo mode on. And I agree, you pretty much can't go beyond that with 1333 mhz memory.

I use OCCT (rather than Prime95) for load testing. I was told by an expert in this field that OCCT was better for i7's, so that's what I use.

With my new setup, I can stress test at about 68-70c under full load at 3.2ghz, and and about 72-74c under full stress at 3.8ghz (due to a slight voltage increase)

I think people should specify when they are measuring core temps or just the "CPU" temp to keep confusion to a minimum.

My Core i7 920 "CPU" idles at 35-40 while the cores are quite a bit hotter around 50c. The cores will hit 80c if I stress test it on Prime 95. These measurements are with the stock fan.

@Prederick

If those are your core temps then those are fine however if it they are the CPU temp I would look into a little aftermarket cooling. Or even better, can you add more airflow through the case?

Edit: That system is running nice and cool Jeff-66. I need to look into a nice, not too expensive, aftermarket cooler that will fit on my EVGA X58.

The good news is that the i7-920 can run all day long, 7 days a week at 85C. The upper limit on that chip is something like 100 to 105c.

Where did you read this? Everything I have read claims that you will want to keep it operating far below that.

EvilDead wrote:
The good news is that the i7-920 can run all day long, 7 days a week at 85C. The upper limit on that chip is something like 100 to 105c.

Where did you read this? Everything I have read claims that you will want to keep it operating far below that.

First off, good point about differentiating between the "CPU temp" (misleading) and the actual core temps. The hottest core is your primary concern.

As for where I heard that about the 'running all day at 85C' thing, I'll clarify. I was told this by an electrical engineer who's degree was from MIT. In fact, everything I posted above I learned from him. His credentials go far beyond his MIT, trust me, but that's not the point, hehe.

His exact words were "it will run all day long, 7 days a week at 85C, but you can expect a shorter lifespan". I didn't post that about the lifespan, because we're talking years. The CPU has about a 10 year lifespan (probably will go longer) at stock speed, so the 85C would maybe reduce that to 6 to 7 years. I don't consider that relevant because A) rarely does anyone keep a CPU that long, and B) no one runs at it 85C all day long.

My point was really that he shouldn't worry too much about 85C under load. The i7 is a tough beast, and it can handle it.

The official intel specs say the i7 920's max temp is 100C. It will likely run at 105C.

edit: found this blurb at PugetSystems:

What we have found is that Intel Core i7 CPUs have extremely good temperature tolerance. Not only are they made with a Hi-K silicon which is able to withstand higher temperatures, but they have very good power management. There are more transistors dedicated to power management on Core i7 CPUs than there were transistors in the original Pentium Pro CPU!

What we’ve found is that the Intel Core i7 CPUs throttle down their speed starting at 100C. So, 100C is the maximum operating temperature of Intel Core i7. However, due to the great power management, we have never seen instability due to temperature. We can run full stress testing at 100C and have no errors. Of course, that’s not a good idea, but my point is that the excellent management features reduce the risk of high temperature.

Thanks for all the info guys. I would note that, after the local temperature dropped and I opened the windows, it's idle temp dropped to around 45C, so it's probably much ado about nothing. I'll make sure to try and get it better ventilation and airflow though. I've been using RealTemp to monitor it, and like I said, i've seen no problems, i'm just twitchy about these kind of things.