Originally Posted by Laithan
I can try to help
Thanks, appreciate it although your set voltages seem quiet extreme. Hope you know what you are doing.
Motherboard MSI P7N2
2x 4GB DDR3 1333MHz Team Group Elite RAM
Scythe Ninja 2 cooler
Enermax Modu82+ 425W PSU
BIOS Options and settings:BIOS Options (Click to show)
D.O.T. Control (1 - 15%) [disabled]
Intel EIST [disabled]
System Clock (Auto, Linked, Unlinked) [unlinked]
Adjust DRAM Frequency [underclocked to 1066 MHz]
Adjust CPU Ratio [6x]
DRAM Timing Mode (Auto / Manual) [stock 9-9-9-24-33-2T timings]
PCI-E Frequency (100-200 Mhz) [100MHz]
MCP PCI-E Frequency (100-200 Mhz) [100MHz]
CPU Voltage 0,0125 - 0,3875 [+0,0625V]
DRAM Voltage (V) 1.50 V - 2.40 V [1.50]
SB Voltage (V) 1.525 V - 2.000 V [1.525]
NB Voltage (V) 1.225 V - 1.600 V [1.35, anything below appeared to be instable]
PCI Expander PLL Voltage 2.551 V - 3.265 V [auto]
DIMM Memory Reference Voltage 0.485 V - 1.200 V [auto]
Memory Terminator Voltage 0.485 V - 1.200 V [auto]
Depending on FSB Terminator Voltage (VTT):
CPU GTL Reference Voltage [0.65-0.666 and 0.668-0.688] (factor of VTT, i.e. 0.65 = 65% of VTT voltage)
NB GTL Reference Voltage [0.591-0.611 and 0.668-0.691] (factor of VTT, i.e. 0.591 = 59,1% of VTT voltage)
FSB Terminator Voltage 1.056 V - 1.313 V [auto] (Also known as VTT on some boards)
SB Sleep Mode Voltage 1.374 V - 1.660 V [auto]
Spread Spectrum (Enable / Disable) [disabled]
Excetute Bit Support [disabled]
As you can see in the spoiler, I underclocked the RAM to 1066 while remaining at stock timings and set the CPU multiplier to 6x so I won't have to adress CPU voltage yet and can concentrate on getting the FSB stable.
For stability testing I am using Prime95 27.9 using Small for CPU Voltage and Large or Custom for checking the FSB (NB ect.).
So, where am I coming from?
Coming from 333MHz FSB, there was quiet a huge hole between around 350-400 MHz.
I managed to get 405 MHz stable with 6x and 8x Multiplier with Prime Small and Large (~6 hours) with:
NB Voltage 1.35V
SB Voltage 1.525V (lowest value I could set)
VTT 1.313 (Highest value I could set, didn't try how much I can turn it down and still stay stable yet.)
CPU Temps during load were around 55-60°C
SPP (NB) Temperature read with HWInfo64 68°C
The NB is quiet hot for my taste, but NVidia says they can go up to ~95°C before they shut off in some way.
Not sure how the temperature effects the OC stability though and since the heatsink is so close to the tower cooler, I won't be able to get some additional fan mounted there anytime soon.
Right now I am trying to get a FSB of 450 MHz stable.
Settings so far are:
CPU +0,0625 (tested with Prime Small, doesn't limit yet since it's still with 6x multi)
First I left VTT, CPU GTL and NB GTL on Auto, but with VTT on Auto I didn't manage to get to the Desktop anymore without the system not POSTing or simply freezing somewhere on the way. So I increased the VTT beginning from the lowest value to make it to the desktop. That would be 1.214V.
After getting into Windows, I tested the FSB with Prime Large first, but it always produced errors after some amount of time. So I tried what test causes these errors the fastest way so I wouldn't waste 30+ Minutes with Large runs before it fails. Turns out the 672k is quiet suited for that purpose.
Then I increased the VTT from 1.214V in small increments up to 1.313V but I couldn't get the system stable after all.
Somehow it gives me headaches since I can't figure out what exactly I am doing wrong. So I came here to see if I could get some help and have a few questions at hand:
1. How do I know what combination of NB Voltage and VTT is "right"?
I messed with it for hours now, setting the NB Voltage (1.35 i.e.) and increasing the VTT in ~0.05V increments. (It regulary has 0.01-0.02 increments.)
But so far, there hasn't been any value I could get stable trough Prime95 Large (672k) for more than 20 minutes without producing errors.
Even if I go for the "give em all you got" way and set the VTT straight to 1.313V for any NB Voltage (1.35/1.38/1.42/1.47/1.5) it won't last long. It appears that too much VTT leads to instability aswell in form of rounding errors, for 1.5V even freezes.
Then I tried to play around with the GTL Voltages for a few of the "better" VTT values (that went close to 20 minutes) but two things seem strange to me:
2.1. From what I read in OC guides, the CPU GTL should be between 61...68% for Wolfdale Dualcores, depending on where you look. Some say it should be equal to the NB GTL which should be at 67%. And then you can read that the NB GTL should be more important than the CPU GTL, but I couldn't find any specific values for it, apart from the 67%.
The point that gives me headaches are the values that I can set in my bios. As mentioned above, the NB goes from x0.591 to x0.611 (small increments of 0.0005) and from x0.668 to x0.691 (wide increments of 0.002). That would be sufficient for the ~x0.67 but what is the fine scaled area between .591 to .611 for?
The CPU GTL, on the other hand, goes from x0.65 to x0.666 and from x0.668 to x0.688. With the recommendation in mind, everything from 61% to <65% is simply out of range for me.
First I thought I mixed up CPU and NB GTL, but I am pretty sure it's this way and not the other way around.
2.2. Sometimes you read that most people only use the GTLs in order to reduce their CPU and NB Voltages by a notch or two, once they got their system stable. Sometimes you read that the GTLs can make the difference between not POSTing and a stable system.In order to find the right GTLs, how should someone start?
Since my VTT isn't stable without adjusting GTLs so far, I can only guess what VTT would be a proper base value for testing.
Then I picked one Prime95 Large FFT lenght that caused the fastest errors for me (672k) and let it run, while setting NB and CPU GTL both at once.
Since I have my CPU multiplier on the lowest setting (6x instead of 8x) and the CPU Voltage is sufficient (Prime Small without errors, freezes or BSODs), can I leave the CPU GTL on Auto and purely concentrate on the NB GTL? Or do the interfere with each other and both have to be on spot at the same time?
The second problem:
I read that you should start with one value x and note how long Prime takes to spill errors / freeze. Then you move in both directions from x (x+y and x-y) and see if the errors / freezes appear faster or slower. With that in mind you see in what direction you have to move and when you get to the right value.
I am not sure if they mean full Prime Large runs with this or not. But I tried it purely with 672k and thought that it would last longer once I get into the right direction.
The problem is, that it appears to be completely random how long this single test runs. If I use the same GTL voltages and let the same test run twice with the same settings, it can happen that it runs for 40 minutes before producing an error in the first run and in the second run it fails after 3 minutes. But if it's completely random within one test and let it run in Prime Large for some amount of time, how would I know if it failed at test #4 and not #3 because it got better and not because I simply got lucky?
In my current understanding, even there I couldn't say for sure if adjusting the GTL +y or -y was good or bad since it could be somewhat random aswell.
I am not sure wether or not there are still people around here that read this and are able to help. I hope there are. Help is appreciated, thank you very much.