SOLVED prime95 Multiplier jumps on fx-8120

I have FX-8120, made better cooling and it was stable overnight with max temp 46C, current core speed 3800 (200x19).
But now i have done small FFTs test for CPU stressing. I noticed my speed droped to 1400 (200x7).
In my BIOS everything is manual and turbo, cool'n'quiet, c6, c1e and thermal throttle is off.
Any advice?

That's a really low multiplier drop... in fact, that's an idle multiplier on my CPU.
This thread might help, but I'm not too sure this is your problem since it drops so low:
http://www.overclockers.com/forums/showthread.php?t=698165&highlight=throttling+temp+related

Do you have Power Options in Control Panel set to High Performance? Is there throttle down technology in your motherboard bios, maybe in PC Health section?

Yes, it is in high performance but i don't think that would affect the cpu in any way.
There is the AMD Power Management, but it is disabled. I will take pictures of my bios and post it in a sec

Don't see anything there that needs changing from those images. Do you have a section in bios that has to do with PC Health, fan speeds, etc. and maybe a motherboard shutdown/throttle down temp adjustment?

I dont have such section. Only Fan speed settings and boot failure guard (enabled)

Don't see a CPUz capture showing the CPU Tab, the Memory Tab nor the SPD tab. Free version HWMonitor from CPUID com open on desktop as P95 is running Blend mode and then the HWMonitor captured showing volts and core temps. I suppose you could run P95 in the same mode you are currntly using as well. Will be needed to keep from just guessing more.

Sounds like VRM throttling since that monitoring and throttle response cannot be shutdown in bios settings.

RGone said:

Sounds like VRM throttling since that monitoring and throttle response cannot be shutdown in bios settings.

Click to expand...

+1, is the H40 mounted at the back of the case, if so is it blowing in?

It is mounted on the back blowing air out.
<--{fan 1900 rpm} [radiator] {fan 1900 rpm} <-- airflow

Front HDD fan blowing air in
bottom fan blowing air up

All the pictures requested

Your core temps look good in HWmonitor but keep in mind that the FX CPUs core temp sensor calibration is significantly skewed on the cool side, I think about 15c and I would point out that your CPU temp is up to 65c. BeepBeep2 in another recent thread ("Look Here: My Top 10 . . .) claims its off by 20c. A Corsair H40 is probably not enough cooler to get much of an overclock on an FX-8xxx.

on different forum guys have written that the CPU temp (CPUTIN) in the senson outside cores, as it is only useful for non-load temp. Cores temperatures are for full-load temperatures.
Link
http://www.overclock.net/t/1128821/amd-temp-information-and-guide

Yes, the CPU sensor is indeed outside the processor die, being embedded in the motherboard socket area. But there is still a correlation between core temp and CPU temp. And you may not be aware of this but the temps reported are not actual real temp measurements as you would think of with a thermometer, they are a calculated value based on several factors, one important one being feedback from the CPU socket temp sensor. On the Thuban and FX processors, the core temp sensor typically is scaled poorly. The best approach seems to be to look at both CPU socket temp and core temp. Personally, when I see more that about a 10c spread between CPU and core temp with good aftermarket air cooling, I tend to rely on the socket temp more which on most AMD CPUs should allow up to about 65c before instability begins to set in.

I changed multiplier to 12.5 = 2500mhz
In blend test on prime95, after 10 minutes 63C, only 2C colder than at 3800

Sometimes, as you are doing, a combination of using the multiplier and the FSB gives the best overclock.

Not everyone but certainly some...

The thread linked below is here in OCF. I found it while looking for Asrock 970 Extreme4 VRM throttling. Since the thread is some 5 months old, I had forgotten it and his solution. YMMV.


You can read the entire thread but I found this one 'again' as I did a search for your throttling issue.

First Post of thread:
i have :asrock 970 extreme4,fx-8150,and antec 300 illusion
Problem 1: The socket temps got up to 70 celcius
Solution: purchase noctua nh-d14
Problem 2: Overclocking made it throttle to 7x200=1400 mhz
this is probably because of the 4+1 power phase rather than a 4+4+2 (8+2) or 4+4+4+2 (12+2) design

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Last edited by dli7319; 02-11-12 at 03:48 PM.

Last post in the 5 page thread:
So just an update, i got a 990fxa-ud5 to replace the 970 Extreme4, only con is no uefi but who needs that


__________________
Antec 300 Illusion Validation
Gigabyte GA-990FXA-UD5 (Hybrid EFI F6)
AMD FX-8150 + Noctua NH-D14
Corsair XMS3 4x4gb DDR3-1600
OCZ Modxstream Pro 700W Power Supply
Sapphire Radeon HD 4850 512 MB
Western Digital Caviar Blue 640GB SATA II
Lite-on IHAS DVD Burner SATA
Gigabyte GM-M6800;Gigabyte GK-K6800
Spare: Asrock 970 Extreme4 + Sempron 145 + FX-8150 cooler + 4x2gb ddr3-1333

I also wonder if putting a spot fan to blow on the socket area would help. I think I have read it does.

So it seems that the 1400 mhz is the motherboard problem. I will think about purchasing air cooler

Just a little more follow-up even though the OP has shown his thead as (Solved).

HWMonitor under load temp of 65c CPUTIN, has caused a cpu Mhz fall back for some of the FX 8 core processor users. In that situation most with a working APM control in bios were able to DISable APM and then the cpu normally would not drop back in Mhz so dramatically when under a P95 load.

Further the move to W/Cooling took away air from the cpu socket and VRM area and increased the heat there. That air flow could be replaced with a fan blowing specifically at those two locations. They would be fairly close to each other.

Some with cases and a motherboard tray open to the back in the cpu area have even put a fan on the rear of the motherboard to lower CPUTIN temps and has helped them pretty dramatically overall.

I have even heard of some users putting a small fan blowing under the motherboard at the top to increase air flow to the rear of the board and lower CPUTIN temps when pushing the hot BD processor.

There have been many crutches resorted to when trying to push a BD processor and have it always run at an overclocked speed and not change frequency because of load on it or the heat involved.

In the end, some have even resorted to a motherboard change for better results. So the crutching seems endless and runs a gamut of things resorted to in order to get some configurations to perform like we think they should based largely on older technology.

I certainly would test a directable fan blowing to overlap the cpu socket and also have air-flow over the VRMs. That might be the cheapest test before doing anything else like even a board swap which maybe the end result.

Good luck to you man and I hope there is a good end to your labors.

RGone, I tried putting a fan behind cpu to lower cputin temperatures, and it is now only 15C more than Core temp at small FFTs prime test.
Before it was 55C at 3.1, now it is 44C at 3.1

Lets overclock now xD