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I5 750 3.8GHz temps abit high?

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June 22, 2010 1:12:06 PM

Hello all,
I recently built my first system and done my first overclock after much research. I am slightly concerned about the temperature my i5 750 at 3.8GHz reaches during Prime.
My system is:
I5 750 at 3.8GHz
CoolerMaster V8
Artic Silver 5
4GB G-Skill Trident 1600MHz CAS8
Asus P7P55D EVO
Corsair TX 650W
1Tb Samsung F3
Asus EAH5850 @ 890/1190 1.5V

After 1 and a half hours of Prime i reached 72/73/67/72 .. and then got an error, so i have more work to do :) 
For a relatively medium overclock with an aftermarket cpu cooler, and with all the intake/exhaust fans in the Antec1200, a 120mm Akasa Viper blowing air onto the V8 and low voltages i am concerned that the temperatures do not reflect all the thermal control.
I got temps in the range of high 70's earlier in the week and then quickly set about fixing the inside of the case by re-routing wires, moving the Viper fan to a better location and also reapplying some more AS5 to the CPU, this has brought the temp down a few degrees but i was expecting better results.
Screeni of the settings after 1.5 hours prime:



I would also like to list the main BIOS settings i am currently running on in the hope you can help me optimize them.

AI Overclock Tuner
AI Overclock Tuner Mode : Manual
CPU Ratio Setting : 19
Intel(R) SpeedStep(TM) Tech : [Enabled]
Xtreme Phase Full Power Mode : [Enabled]
BCLK Frequency : 200MHz
PCIE Frequency : 100MHz
DRAM Frequency : 1600MHz
QPI Frequency : [Auto]
CPU Differential Amplitude [Auto]
CPU Clock Skew [Auto]

DRAM Timing Control Sub Menu
DRAM CAS# Latency (tCL ) :8
DRAM RAS# to CAS# Delay (tRCD ) :8
DRAM RAS# PRE Tine (tRP) :8
DRAM RAS# ACT Tine (tRAS) :24
Timing Mode (CMDR) :2N
(Everything else on Auto)

AI Overclock Tuner Continued
CPU Voltage Mode : [Manual]
Offset Voltage : 1.18750
IMC Voltage : 1.20000
DRAM Voltage : 1.6000
CPU PLL Voltage : 1.80
PCH Voltage : 1.05
Load Line Calibration : [Enabled]
CPU Spread Spectrum : [Disabled]
PCIE Spread Spectrum : [Disabled]

CPU Settings
CPU Ratio Setting : 19
C1E Support : [Enabled]
Hardware Prefetcher : [Enabled]
Adjacent Cache Line Prefetch : [Enabled]
Max CPUID Value Limit : [Disabled]
Intel (R) Virtualization Tech : [Disabled]
CPU TM Function : [Enabled]
Execute-Disable Bit Capability : [Enabled]
Active Processor Cores : [All]
A2OM : [Disabled]
Intel(R) SpeedStep(TI1) Tech : [Enabled]
Intel C-Start Tech + : [Enabled]
C State package limit setting [Auto]

Any help with the BIOS and settings is greatly appreciated, though i would add i would like to remain at 3.8GHz or drop to 3.6GHz.
Thanks alot for taking time to read this :D 
Stephen
June 22, 2010 1:41:26 PM

At those temps, I would seriously suggest going over to watercooling. Air cooling can only take you so far.

You should switch off CPU TM function, and Speedstep. They can cause glitches with overclocking, especially when taken as far as you have.

If you do not want to go to the expense, effort, and time to fit watercooling, increase the airflow as far as possible - which can get very noisy.

The last system I OCed (a P4 631 3GHz) would start throwing errors at 70ºC/5.3GHz. At 5.5, it would hit 78ºC within 15s and BSOD during startup. I usually ran it at around 4.8GHz, with an average temp of 68ºC. And that was WITH watercooling... the highest I could get it on air was 3.6GHz, and Prime failed then already within 30 minutes.

Currently, the i5 I replaced that rig with is at stock settings and on air. Until it starts either getting laggy or I get bored... [insert insane laughter here]

Hope this helps...
a b à CPUs
a b K Overclocking
June 22, 2010 1:45:22 PM

stephenm1 said:
For a relatively medium overclock with an aftermarket cpu cooler, and with all the intake/exhaust fans in the Antec1200, a 120mm Akasa Viper blowing air onto the V8 and low voltages i am concerned that the temperatures do not reflect all the thermal control.

Going from 2.6 to 3.8, there's nothing medium about that, not too long ago that would have taken exotic cooling (phase/LN2) to do it, geeze I'm showing my old age.

Couple of things you can do since you are very close, run Prime95 (small FFT) for a couple of hours and see if you get any errors. This will isolate your CPU OC, so if it passes you can be pretty sure it's your ram, then you can work on your VTT,vDimm,PLL voltages to see what you need for stability. Running an hour and a half before an error means it won't take much.

As for your temps, although not great, your still not in any danger zone. Intel's spec for your processor is 72.7c (Tcase temp) so even mid 70's is still within specs but as with all temps and voltages when OCing lower is better, it just depends on your comfort level.


Related resources
June 22, 2010 2:44:03 PM

2.6 - 3.8 needing LN2 would probably have been during the early Northwood/Preshott days. The Cedar Mill was a lot better in that regard.

Or how about the days when liquid cooling was considered exotic? Now those were fun times...

*gets hit by a bus down memory lane*
a b à CPUs
a b K Overclocking
June 22, 2010 5:43:26 PM

The kids now a days have it so easy, push a button to OC to 3.6 Ghz (although it tends to overvolt the hell out of it) it used to actually take some work, as you know, glad to see some of them will still learn about the Bios settings and do it the right way though.

Times always change though, it's hell getting old. I've even got a few friends (not many though) that refuse to even use a computer and won't even acknowledge there's a thing called e-mail. :lol: 
June 22, 2010 10:27:07 PM

I have my i5-750 at 3.8 stable also, and it idles at around 35-38c in an 18-20c ambient room temperature. I'm not too sure if this is worth it but perhaps you could consider replacing your cooler to a... possibly more high-end one? I don't know too much about the V8, but how does it fare with the Megahalems and Venomous X coolers?
a c 229 à CPUs
a c 163 K Overclocking
June 23, 2010 2:14:28 AM

The case is not the problem....but the cooler is not the best. I'd replace the V8 / AS5 with the Megahlems and IC Diamond. AT the very least, replace the AS5 unless you wanna wait for the 200 hours and necessary thermal cycles for it to cure. My son's 920 runs at 3.8 in the mid 50's in the Antec 1200. At 4.0 - 4.2 Ghz, he's hitting temps similar to yours but running stable.

I'd also suggest undervolting the CPU a bit....he's got his at 1.125 which dropped the temps significantly ...had it a bit lower for a while but it would get wiggly every cupla days.....so he upped to 1.125 and been stable ever since.
June 23, 2010 11:38:57 AM

RJR said:

Couple of things you can do since you are very close, run Prime95 (small FFT) for a couple of hours and see if you get any errors. This will isolate your CPU OC, so if it passes you can be pretty sure it's your ram, then you can work on your VTT,vDimm,PLL voltages to see what you need for stability. Running an hour and a half before an error means it won't take much.



Firstly, Thank you all for the reply's.
I have disabled Speedstep and CPU TM as Mugz said. Watercooling wise im not really wanting to spend more money upgrading the system, if it means i drop to 3.6GHz to get better temps then so be it.
I've ran Small FFT in prime95 for 2 hours 15mins and have got no errors, with the temps maxing at 71/71/65/70.
So i have a RAM problem?
I am running the RAM at the specs it was said to be at on the website, 8-8-8-25-2N 1.6V 1600MHz. If the RAM is the problem how do i fix it?

Thanks for all your help, its very much appreciated.
Stephen
June 23, 2010 2:40:31 PM

Another option, air-cooling wise, would be the Cooler Master V10. Although since that one incorporates a thermocouple-based heat pump (a.k.a. Peltier unit) it will have a HUGE power draw.

The other problem with Peltiers is their mediocre output, given their input power needs and high cost.

I still think that we should start making heat sinks black again, for maximum heat radiation.
a b à CPUs
a b K Overclocking
June 23, 2010 11:24:50 PM

stephenm1 said:
I am running the RAM at the specs it was said to be at on the website, 8-8-8-25-2N 1.6V 1600MHz. If the RAM is the problem how do i fix it?

Lots of things you can try:

vdimm : up to the max of 1.65v
QPI/VTT voltage (IMC in your Bios) : max of 1.21v, the higher the bclk the higher you usually have to set this
PLL voltage : 1.89v max
PCH voltage : forget the max off the top of my head but upping it to 1.10v is safe, you can check out Intels data sheet to see all the recommended voltages
2N to 1N : should make it harder to stabilize but stranger things have happened

any or all these can be changed safely and then tested, once you have stability you can start lowering and testing to find the sweet spot

You can also try 20 X 190, keeping your same frequency but with a lower Bclk some of your voltages will be able to be lowered and if your board allows you to lock the multiplier at 21 you can try that also (some do, some don't).

It's a trial and error deal and lots of testing to find the sweet spot, good luck.
!