I am finally ready to start OC the below modest box (phenom 945). I plan on getting a real air cooler shortly but wanted to understand the impacts amongst vcore, ht etc. I have read numerous guides, most of which are consistent, and still have a few questions. I prefer to get as far as i can with AMD overdrive and then go to the BIOS Setting to save some time.
1. Diagram - I tend to prefer pictures to understand the relationships between the vcore voltage, ht timings etc. Is there a diagram
the outlines the major elements in overclocking for beginners?
2. General Sequence - I believe the approach for is as follows. I have divided into two phases - phase 1 gets you close and phase II dials it into the final value. I like a decent amount of safety margin.
a. Set up your memory in BIOS at the supplier rated speed and timings
b. Set all the elements in BIOS to manual (vs auto) at the stock settings for
- vcore (1.35)
- cpu(core) multiplier
- ht ref clock
- ht multiplier
- nb vid voltage (1.2)
c. elements to save for Phase II (DRAM , HT & SB voltage)
d. don't bother touching PCIe speed ever
e. Start the big dial /Phase I
Now, since i have a fixed multiplier on the 945 (15)
Loop through the following
-Up the HT reference clock by a few MHz (using AOD)
- If it fails, lower the multiplier and restart with the higher HT reference clock.
Until unable to go farther
Now here is where I get a little stuck.
I have only gotten to 3.165 , HT clock 210 (which pops mem to 840) using AOD. The AOD locks up when I go higher.
If the system doesn't boot with a lower multiplier and higher freq, should I goose the vcore?
Do I set it up a little bit more and go back to the loop? I am loath to add vcore as i work in the embedded HW industry.
I believe that third variable (vcore) is the only element left in this loop.
OR do I go back to the loop in the BIOS and assume the save from AOD is failing somehow.
I prefer to maintain the power saving functions because maxing out the clock and vcore 24/7 seems like sitting at a stop light, with the car in park, while holding the gas pedal to the floor and listening to the engine bounce off the rev limiter......when the car just needs to sit there and power the AC and the radio.
The advantage of the maxed out 24/7 approach is that you may be able to overclock just a little further with the clock speed and voltage "locked down" rather than changing with load. But it's probably only a couple 100 mhz difference.
Software CPU overclocking is generally less effective than BIOS overclocking, so I wouldn't go that route for maxed-out or dynamic overclocking. (GPU -video card- overclocking software seems to work well though)
Here is a cut and paste on how I overclocked my 1045t and kept variable Vcore and clock speed: (from another thread)
I have my 1045t OC'd to 3.4 Ghz with all 6 cores running. It could go higher but, I'm limited by heat because I can't fit a bigger cooler in my case.
I recommend getting some free software first. CPU-Z and HWmonitor, and prime95.
CPU-Z will show you frequencies, voltages and ram timings.
HWmonitor will show you temps. *Be warned* HWmonitor was showing my core temps 10 degrees lower than they actually were. The temp labeled "TMPIN2" was actually tracking perfectly with the core temps shown in AMD Overdive. So look for the highest temperature other than your video card. (many video cards can safely run at hotter temps than your CPU.) The hottest one on my Gigabyte 990 fxa ud3 (other than the video card) is the core temp. Try to keep it below 55C under full load.
Prime95 is the program that will stress test your computer to see if it can remain stable and cool under load. 2hrs of the blend test with no errors and no overheating is a general rule of thumb for a stable OC.
Now for the fun stuff.
Go into your BIOS and lower the multiples for your CPU and your Ram by a few steps. (The 1045t won't let you increase the multiplier above stock)
Then disable turbo (aka "core performance boost" )
Then find your CPU Host clock control and set it to "manual"
Then You should be able to change the "CPU Frequency" (I'll call it FSB) (This is before the multiplier, so it will be low. Mine started at 200)
Now increase that variable by a bit.
I recommend balancing your FSB and your "memory clock" (RAM) multiplier to a point where your ram is back down to stock speeds after you bump the FSB. So raise your FSB to something like 250 then adjust your RAM multiplier down so that your RAM us running at or near stock speeds.
Now move on to your CPU clock ratio. With the faster FSB, you will be able to run your CPU at higher frequencies with a lower-than-stock multiplier. I eventually took mine all the way back up to 13.5 with a final frequency of 3.4 Ghz.
I would recommend starting with a lower multiple that gets you just a couple hundred Mhz boost over stock at first. Then test for stability and heat. Run prime 95 for at least 30 minutes if you want to see your hottest temps. The blend doesn't get things hot until about the third bank of tests.
If things look good, go back into the BIOS and bump the multiplier some more and re-test.
My MB got rather ambitious with the voltages when I left it in auto, so use CPU-Z to keep an eye on core voltages. Many recommend just staying under 1.45 volts. I recommend not going any higher than you need to for a given clock speed. This will help keep heat down. I ended up using a negative offset "CPU voltage control" of -0.075 volts. This brought my core voltages down to about 1.344v at full load.
*note* I'm scraping the floor on voltage with my particular chip/speed. One notch lower and I get BSOD. You may be able to go a little lower or you may need a little more voltage for your chip and clock speed.
Now just test and adjust and repeat.
BSOD means you need more voltage, and/or less speed.
Overheating means you need less voltage and/or less speed. (or a better cooler for your CPU.)
If you get to the point where your temps are good and your computer is sable, and you still want to go faster (than ~3.4Ghz), you can go back and bump up the FSB. But remember to adjust your RAM multiplier back down to stock-ish speeds.
You can OC your RAM later, but that gets a little more complicated as you may have to adjust CAS timings and RAM voltages to make it work. Keeping your RAM at stock speeds should give you one less thing to worry about while you probe the limits of your CPU.