FX8320 Multiplier Changing Under Load

[19Andrew]

Hi,

Overclocked my CPU to 4.8GHz @ 1.5V.
When I run Prime95 the CPU multiplier (According to CPU-Z) is constantly changing (BTW ran Prime95 for 15-20mins on small FFT and none of the cores stopped).

I've disabled things like Cool'n'quiet, C1 and C6 state.

Is there anyway to get this changed to a constant multiplier or does this just happen under load?

Thanks

Specs:
AMD FX-8320
GTX 770
Gigabyte 990XA-UD3 (8+2 phase)
4GB DDR3 Crucial Tracer RAM

 

[darkmendez]

have you ever thought of getting more RAM? 4gigs on a 8-core processor?

 

[Soulage]

Going to need more info to determine why it's changing.

To start with since you didn't list one please tell me you are not using the stock cooler?
What changes did you make exactly in BIOS?
Can you post some screen shots of monitoring software such as HWMonitor/HWInfo with all the CPU bits open under load?
Just incase, what PSU are you using?

 

[19Andrew]

have you ever thought of getting more RAM? 4gigs on a 8-core processor?

I am planning on getting another 4gigs but as of this minute im using a 32bit OS. I am going to be upgrading to 64bit when windows 10 comes around.

 

[19Andrew]

Going to need more info to determine why it's changing.

To start with since you didn't list one please tell me you are not using the stock cooler?
What changes did you make exactly in BIOS?
Can you post some screen shots of monitoring software such as HWMonitor/HWInfo with all the CPU bits open under load?
Just incase, what PSU are you using?

Cooler is a H80 in pull.
I changed the multiplier from 17.50 (stock) to 24.00 (OC). Voltage up by +0.100V. Also increased voltage on DRAM from 1.5V to 1.515V
PSU is a Xigmatek Tauro 700W 80+ Bronze.

I will try and get some screen shots for you.

 

[darkmendez]

you can doubt me if you like......but RAM and also the motherboard plays a bigger role than you think. If u are using a 64-bit operating system, you are putting stress your PC big time! I'm using FX-8350, 32GB of RAM, GTX 970(Small version), 3TB Hard Drive, 850 Watt with 75Amps PSU.

 

[19Andrew]

you can doubt me if you like......but RAM and also the motherboard plays a bigger role than you think. If u are using a 64-bit operating system, you are putting stress your PC big time! I'm using FX-8350, 32GB of RAM, GTX 970(Small version), 3TB Hard Drive, 850 Watt with 75Amps PSU.

Ok, im still fairly new to building a PC and Overclocking but I will do that if anything else doesn't fix it. Thanks

 

[cdrkf]

Hi,

Overclocked my CPU to 4.8GHz @ 1.5V.
When I run Prime95 the CPU multiplier (According to CPU-Z) is constantly changing (BTW ran Prime95 for 15-20mins on small FFT and none of the cores stopped).

I've disabled things like Cool'n'quiet, C1 and C6 state.

Is there anyway to get this changed to a constant multiplier or does this just happen under load?

Thanks

Specs:
AMD FX-8320
GTX 770
Gigabyte 990XA-UD3 (8+2 phase)
4GB DDR3 Crucial Tracer RAM

All FX CPU's have a built in thermal throttle, if the cpu temp exceeds 65 degrees, it throttles back. That is real possibility if running Prime95, what are your temp readings like?

 

[darkmendez]

19Andrew....good job....try to change your RAM to dual channel memory instead of single-memory. So your load time won't look so funky.

 

[19Andrew]

All FX CPU's have a built in thermal throttle, if the cpu temp exceeds 65 degrees, it throttles back. That is real possibility if running Prime95, what are your temp readings like?

Yes its going just over at 68*C. I would bring up screen shots but im not sure how to.
Ill try backing off the voltage just a touch.

 

[cdrkf]

All FX CPU's have a built in thermal throttle, if the cpu temp exceeds 65 degrees, it throttles back. That is real possibility if running Prime95, what are your temp readings like?

Yes its going just over at 68*C. I would bring up screen shots but im not sure how to.
Ill try backing off the voltage just a touch.

Yeah that's your issue then. You may also need to improve airflow in your case- a couple of case fans can work wonders. As a stop gap you can also try running with the sides off the case (if that fixes it airflow is what you need).

 

[19Andrew]

Yeah that's your issue then. You may also need to improve airflow in your case- a couple of case fans can work wonders. As a stop gap you can also try running with the sides off the case (if that fixes it airflow is what you need).

I will go and try and get some more fans to improve the temps, any suggestions on a decent set? I have a corsair carbide 300R case so 120mm and 140mm are my only size options.

 

[darkmendez]

19Andrew.....get an air compressor or air in a can to blow out the fans

 

[19Andrew]

Ok, was about to reduce voltage but then I realized that I could turn my fan speed up, it was on the first silent setting on the H80 controller, did that and its gone to 58*C max temp, but still same problem. However I have noticed that under load the Core Voltage fluctuates and in tandem with the multiplier.
The voltage then remains constant at idle along with the multiplier.

 

[Soulage]

If it's still doing it with 58c as your max temp and no thermal throttling going on it could be an overlooked BIOS setting.

LLC (Load Line Calibration) is what combats vdroop when the CPU is under load (voltage dropping as it is stressed).
APM (Application Power Management) could also be causing it along with needing to enable HPC (High Performance Computing).

1st try it with APM disabled, if it carries on try turning on HPC, if the voltage is still lowering the clock speed (although with those disabled and enabled it shouldn't) you will need to find a level of LLC that keeps it stable.

Just be careful about adding any more voltage as you're already at 1.5V and that's pretty high as it is, I don't think your cooler would manage much more and then the thermal throttling would kick in again. You could still try dialing back the voltage in steps to see if you can remain stable at 4.8 on a lower amount.

 

[19Andrew]

If it's still doing it with 58c as your max temp and no thermal throttling going on it could be an overlooked BIOS setting.

LLC (Load Line Calibration) is what combats vdroop when the CPU is under load (voltage dropping as it is stressed).
APM (Application Power Management) could also be causing it along with needing to enable HPC (High Performance Computing).

1st try it with APM disabled, if it carries on try turning on HPC, if the voltage is still lowering the clock speed (although with those disabled and enabled it shouldn't) you will need to find a level of LLC that keeps it stable.

Just be careful about adding any more voltage as you're already at 1.5V and that's pretty high as it is, I don't think your cooler would manage much more and then the thermal throttling would kick in again. You could still try dialing back the voltage in steps to see if you can remain stable at 4.8 on a lower amount.

Thanks I will give this a shot now!

 

[Calculatron]

What revision of the the UD3 do you have? The earlier revisions don't have good VRM cooling. If you are pumping a lot of voltage through your system, it may be that your CPU is keeping cool, but your VRM is overheating with such a load.