CPU generations burned to 0.09 microns (heart Venice to Palermo for Athlon or Sempron) opens new prospects for overclocking.
The heat loss of this generation is low, allowing gains significant frequency without heating important (as long as it has a well-ventilated housing and a good heatpipe)
This change allows the less fortunate (but DIY) by setting up a low-cost, developing a power equivalent to a CPU much more expensive.
In its preamble, I recall that this practice can lead to serious malfunctions of your system, possibly irreversibly damaging some electronic components.
I advise you to download and install the software CPUZ to monitor developments frequencies of your system and other enabling monitoring of temperature and system stability (Motherboard Monitor for temperature, and Super OCCT Pi to test the stability).
But go to the heart of the matter.
I would not distinguish between 754 and 939 sockets or the recent AM2 (+) which manages the DDR2, the approach is substantially the same.
The 64-bit architecture from AMD has changed the approach to the subject.
We must distinguish three distinct elements to achieve a good overclocking:
The HTT, which represents the operating frequency of CPU, set at 200Mhz for these platforms.
- On sockets A, it was called FSB.
- Multiplied by the coefficient (the increase is blocked at AMD, except on FX) CPU, it gives the working frequency of the processor.
- Ex: For an Athlon 64 3000 +, 1.8 Ghz:
- Frequency HTT = 200 multiplied by the coefficient (9) = 1800MHz
HT or Hyper transport bus, not to be confused with the HTT.
- It is the main feature of these motherboards, is a bus for the exchange of information between the CPU and chipset.
- Its frequency is 800Mhz for most Socket 754 and 1000Mhz for 939.
- Behind this frequency, we find the HTT (200Mhz) which is applied a multiplier.
- Problem: this bus does almost no elevation, but we shall return later.
The frequency memory.
By default, it is preferable to use the DDR400, in this way, it will be synchronous with the HTT. In all cases, behind the choice of frequency bios, this cache, too ratios (1 / 1 for DDR400) over the HTT.
You're with the basic level to understand how an AMD platform.
What now?
Increase HTT!
Yes.
So we increase this parameter via the bios, to 205, then 210, then 215, and ........ crash!
Because our bus crash HT, as I said earlier, does not support a surge.
Out of HTT to 215, the bus rose to 1075Mhz (such as I keep the Athlon 64 3000 + socket 939). Behind this lies the frequency multiplier x5. But most bios allow us to reduce this multiplier.
We'll get to the x4 (4 x 200 = 800), because we must remember that we must never exceed the maximum bus HT (1000 in our example and do not worry about the possible negative effect on lowering the performance, because it can fall to 600Mhz without feeling lower overall scheme)
Warning:
Never increase the HTT too fast, not always 5MHz, testing the well each time, and monitor temperature.
Resuming the increase in the HTT.
215, 220, 225, 230 ......
This is but the PC is unstable, this time, the memory limits us.
Our CPU is still at 9 x 230 = 2070 Mhz, so a little more than a 3200 +.
HT bus is 4 x 230 = 920, this side, so good.
But it is possible to go further, because in reality it is likely that your DDR400, pushed to 230, has already shown its limits.
The first solution is to take the quality RAM DDR533, leaving much room for maneuver.
This solution has the advantage of letting the memory synchronous with the HTT, which helps maintain high bandwidth, especially on socket 939 that run in dual channel, which influence significantly the performance.
Problem: the price!
The alternative is to desynchronizing memory.
This way is less costly because a good DDR400 will be the case (I advise the "noname" but a "Value RAM" a good manufacturer)
In passing the memory frequency in the BIOS to "DDR333" (or PC2700), you apply a ratio relative to the frequency HTT CPU (9 / 11 for DDR333 in our example)
So when we HTT of 230MHz, memory frequency was 230 x 9 / 11 = 188Mhz.
A 240 of HTT, our DDR 196Mhz is perfect.
HT stands at 960, very well.
The CPU is now running at 2160Mhz, which is virtually a 3500 +!
To check, just to test your setup with a Benchmark whatsoever.
- In the case developed above, it is possible to climb even higher, but the settings I have settings that should go on a large number of configurations, if your motherboard is well designed and it is safe bet that the heatpipe original enough to cool your CPU correctly, and that stability is correct.
- It is possible that you never get there, because of repeated crashes. In this case, you should slightly increase the supply voltages of CPU and / or memory.
- It is against difficult to give a way forward, as the case may be different but overall, we must ensure that it does not exceed 1.8V of the CPU Vcore and 2.8V for DDR.
- Beyond that, there are more risks and it falls into the advanced overclocking, which is not the issue.
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