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New PSU = Higher cpu Temps.Follow

#1 Mar 17 2012 at 2:24 AM Rating: Good
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So, long(ish) story short, I switched from an 850 watt psu (not sure about brand or model) to a Corsair AX750. Full specs are:

Intel i5 2500k, Stock cooler and no overclocking.
Asus P67 Sabertooth
4GB Corsair Vengeance
MSI Twin Frozr III GTX 570 (Also running slightly hotter than usual, thought not as much as the cpu is)
Seagate Barracuda 1TB
Intel 320 series 120GB SSD
WD Elements external HDD, permanently connected
The aforementioned Corsair AX750.

After installing the new PSU, temps jumped from around 35C to 40-44 C at idle. I was mostly just wondering if the reduced power availability would result in higher temps.

#2 Mar 17 2012 at 2:42 AM Rating: Decent
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More than likely the older PSU was moving air through the case in a way the newer one isn't.

Corsairs often have fans on the top or bottom of the PSU depending on what type of case it's designed for. If you weren't paying attention, you may have put that fan directly against the case, almost completely killing your airflow.
#3 Mar 17 2012 at 2:50 AM Rating: Excellent
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Yeah, That or the old PSU was installed upside down from how you have the new one. You might also want to check that you didn't knock a fan cable loose when you installed the new PSU or forgot to plug one in. Or have a PSU cable stuck in a fan so it isn't spinning.if you have a smaller case with only a few fans that can make a huge difference.
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#4 Mar 17 2012 at 3:21 AM Rating: Good
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All the fans are running, and the PSU fan is facing the floor, as the case (CM Storm Scout) dictates. The only thing I can think of is I actually knocked the CPU heatsink while I was messing around and I just have to resit it, but that doesn't explain why the GPU is hotter than normal (around 46C idle). Also, ambient temp is probably around 30C.
#5 Mar 17 2012 at 3:46 AM Rating: Excellent
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46c isn't actually a bad idle temperature for most video cards. maybe the 850 watt PSU just had a really large fan in it. How many fans are in your case currently? if PSU airflow really affected it that much, it might be time to step up to something more efficient.
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#6 Mar 17 2012 at 4:21 AM Rating: Good
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Quote:
46c isn't actually a bad idle temperature for most video cards. maybe the 850 watt PSU just had a really large fan in it. How many fans are in your case currently? if PSU airflow really affected it that much, it might be time to step up to something more efficient.


Two 120mm fans on the side, a 120mm exhaust on the back, a 140 front intake, another 140 on the top, then the CPU fan, and the two fans on the GPU. Compared to my old cases one 60mm side, one 60mm rear exhaust and one 120mm front intake as well as the CPU fan and however many fans were in a GTX 260

I was thinking about just going all out and buying a CM HAF X or 932 (my dream case, for some reason) and setting up some sort of liquid cooling loop for my CPU, although that's beyond my knowledge at the moment, it's not out of my price range, and I know a few people who might help me get started.
#7 Mar 18 2012 at 7:54 PM Rating: Good
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Ok, so, I cleaned off all the thermal paste, reapplied it, and remounted my heatsink. Idle temps are lower than they were before, so I tested it with a game (Skyrim). CPU climbed to 92 degrees, GPU stays at Idle temp, and does nothing whatsoever. Not sure if it's pertinent to the problem, but I'm hoping it helps anyone with more of a brain than me for these things.
#8 Mar 18 2012 at 11:33 PM Rating: Decent
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Without taking into account the specific behavior of that CPU, that temp is high, very high, possibly critical limit high. How much thermal paste did you use?

Edit: Some quick Googleing is showing that you should be in the 50-60 range. 92 is probably close to critical.

Edited, Mar 18th 2012 7:43pm by Raolan
#9 Mar 18 2012 at 11:48 PM Rating: Excellent
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Yeah 92, if thats celcius, there is somethign seriously wrong with your heatsync installation. The motherboard should be going into thermal protection mode. Any chance thats fahrenheit instead? If its not, shut that computer down immidiatly.

If its the stock heatsync, you may have one of the plastic peg pieces bent over and causing the heat sync to lift off the CPU. Try reseating it, and if that doesn't work, consider purchasing a different heat sync that is easier to install.

Also your thermal paste layer should be fairly thin. the newer I7 heat sync's will generally apply enough force that even if it is too thick it will thin out, eventually, but that could be causing some issues
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#10 Mar 19 2012 at 2:13 AM Rating: Good
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Two of the plastic pins were bent on the stock cooler, so I fixed that, hoping that would fix the problem. It didn't. So, I reapplied thermal paste, same amount as always, about the size of a Canadian dime, probably less. When I removed the cooler, it's spreads so that the only parts not covered on the CPU are the edges. Pretty thin layer.

And yes, 92 Celsius, I promptly shut down. The heat sink is definitely installed correctly, it's really snug, not coming apart from the motherboard in any way. I've been racking my brain to try and figure out what could be the problem, and the only thing I can think of is faulty sensors on the motherboard, or there's something really, really wrong with my CPU. Just with one chrome tab open, and skype running in the background, it's at 55C, which leads me to believe the CPU is at fault, unless the sensors are buggered, but I'd rather not take that chance.
#11 Mar 19 2012 at 2:50 AM Rating: Decent
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I'm not sure how big a Canadian dime is, but "grain of rice" is an often repeated measurement. If it's anything like a US dime, that's too much. Thermal paste is pretty much just there to ensure even contact between the CPU and heatsink. Too much and it starts to behave like an insulator.

What are the other cores reading at and what are you using to measure them?
#12 Mar 19 2012 at 3:40 AM Rating: Good
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Canadian dime is much larger than a grain of rice. Cores are at 54, 52, 49, 50, cores 0-3 respectively, as I'm writing this. I'm using Hardware Monitor to monitor temps, if you like, I can upload a screenshot of the window so you can glean more info from it.
#13 Mar 19 2012 at 4:15 AM Rating: Decent
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I just wanted to make sure that all the cores were being monitored, that they were reading at similar temps, and that you weren't using some obscure monitor. No need for screenshots right now.

You would be surprised at how little thermal paste you really need. A metal on metal connection is not going to be air tight. The purpose of the thermal paste is just to remove those tiny little gaps and move heat between the CPU and heatsink more efficiently. Any more than what is needed to make the connection between the two pieces of metal will begin to trap the heat within the paste and reduce its efficiency.


Back to the original problem.

You said that your PSU has the fan pointing to the bottom of the case? But that case has a bottom mounted PSU. Is it pressed against a flat piece of metal or is that ventilated? Either way, you need to make sure that's not an intake. If it is, it's going to be sucking up crap from under the case, or not getting any airflow at all. Either way, that would easily explain the higher idle temps over your old PSU. If that fan is smashed against the bottom of the case, it's providing zero airflow inside your case. There's also a good chance you'll smoke that PSU as soon as you put it under any serious load.

Personally, I would say ***** the directions. Turn that PSU over so the fan is pointing up before you fry your system.
#14 Mar 19 2012 at 8:10 AM Rating: Excellent
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If the heat sync itself is on correctly, and the thermal compound is spread evenly, you might be running into a bad CPU heatsync fan. That fan by itself should be keeping the CPU at around 42c at idle regardless of the rest of your case configuration. Maybe a broken tachometer wire in the fan lead? That or potentially if your motherboard lacks thermal protection you may have partially cooked your CPU, which will generally result in higher temperatures and lotsd of bluescreens. That or possibly the termal compound you are using is junk, but if its Artic silver or equivelent it should be ok. A dime sized coolent blob is a bit much, but if that was spread around sufficiently it probably wouldn't impeed cooling too badly.

Was there any scorching or discoloration of the metal on top of the CPU itself when you pulled the heatsync off?
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#15 Mar 19 2012 at 12:20 PM Rating: Good
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Raolan wrote:
You said that your PSU has the fan pointing to the bottom of the case? But that case has a bottom mounted PSU. Is it pressed against a flat piece of metal or is that ventilated? Either way, you need to make sure that's not an intake. If it is, it's going to be sucking up crap from under the case, or not getting any airflow at all. Either way, that would easily explain the higher idle temps over your old PSU. If that fan is smashed against the bottom of the case, it's providing zero airflow inside your case. There's also a good chance you'll smoke that PSU as soon as you put it under any serious load.

Personally, I would say ***** the directions. Turn that PSU over so the fan is pointing up before you fry your system.

The PSU fan isn't facing straight against the case, there's a hole in it, covered with a mesh foam to allow airflow. Also, this might seem like a stupid question, but is there a way to tell if your fans are moving heat in or out other than just holding your hand next to it?


Dread Lörd Kaolian wrote:
If the heat sync itself is on correctly, and the thermal compound is spread evenly, you might be running into a bad CPU heatsync fan. That fan by itself should be keeping the CPU at around 42c at idle regardless of the rest of your case configuration. Maybe a broken tachometer wire in the fan lead? That or potentially if your motherboard lacks thermal protection you may have partially cooked your CPU, which will generally result in higher temperatures and lotsd of bluescreens. That or possibly the termal compound you are using is junk, but if its Artic silver or equivelent it should be ok. A dime sized coolent blob is a bit much, but if that was spread around sufficiently it probably wouldn't impeed cooling too badly.

Was there any scorching or discoloration of the metal on top of the CPU itself when you pulled the heatsync off?

There was slight burn marks on the CPU the first time I tried to remount it, so hopefully I haven't completely fried it.
#16 Mar 19 2012 at 1:51 PM Rating: Excellent
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Burn marks = bad. You may want to start thinking about a new cpu. As for fan airflow, on a standard computer fan, the bracket that holds the fan motor that the fan itself mounts to is the back. Air flows in the front and out the back. If you want an intake fan, the bracket should be away from the mountimg screws into the case. For an exhaust fan, the bracket should be touching the exhaust point.

Given the temperatures you are recording, there is. A good chance you damaged either the cpu or just the thermal sensor.
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