Thursday, March 10, 2011

Hexaputer Overclocking

You might be asking 'Why do you want to overclock a hexaputer?'. As I indicated in my original post, AMD processors have not kept up with Intel in recent years, but they represent a great performance per dollar proposition.

Especially, when you buy a Black Edition CPU like I did.

Way back in the dark ages of computers, people discovered you could run them faster than 'stock'. Early 8088 machines often had a 'Turbo' switch, which was usually superfluous, because (at least on my machines) it remained forever in one position......ON......

Later, computer manufactures started to get in on the game. They bought cheap low rated CPUs from Intel, overclocked them, and sold them to consumers as higher end PCs. Intel didn't like that, and savvy computer users knew they could do the same thing (for less), but then, as now, savvy users were at a premium.

Feeling left out of the party Intel (and later AMD) locked down what is referred to as the multiplier on the chip.

CPU speeds are determined by two things. The core bus speed, and the multiplier. If the multiplier is locked then you can't overclock the system that way. You can only mess with the bus speed. Note, jacking up the bus speed isn't a bad approach, but as I will detail, it can raise some issues.

Both AMD and Intel sell 'unlocked' versions of their CPUs. AMD charges a lot less for those than Intel does. AMD refers to them as 'Black Edition' CPUs, while I believe Intel usually appends an X to the CPU designation (eg. i7-980X, and yeah, go ahead, price one of those).

So my CPU is the (current) top of the line AMD 1100, in an unlocked Black Edition.

It turns out, that the initial overclocking I did via the motherboard's automated system, assumed I was using a 'locked' multiplier. So it didn't try to change it. For the 1100, the default multiplier is 16.5 and the bus speed is 200. Multiplying the two numbers yields 3300, which is the stock speed of 3.3 GHz.

When the motherboard's AI Overclock feature upped the system bus speed, it downgraded the speed of the memory to the next level to ensure the system would boot. Trying to force the system to apply the correct timings for 1333 RAM failed. So, with the 'bus overclock' approach, the system clock was around 3.8 GHz, but the RAM was running with a transfer rate around 980. Not exactly what I would call a great result.

I wanted 4+ GHz and 1333 RAM. And I got it.

The first step was to save the AI Overclock configuration. The ASUS Crosshair IV Formula motherboard lets you save (I think) 8 different BIOS profiles.

Next, I reset the BIOS to the factory defaults. This is where paying attention to which drive went into which SATA port would've paid off. When I did that, and rebooted, the system tried to boot into XP because it found the old 1TB XP System Drive. XP of course was horribly confused. It went to sleep in an NVidia world and woke up in an ATI one. I rebooted, re-configured the boot drives, then saved that configuration as well.

Once back in Windows 7 I verified that the memory was running at 1333 MHz via CPU-Z....sure enough. All good. Then, I went back into the BIOS and explicitly set the RAM settings.

DDR3 RAM usually has at least four numbers associated with it. Mine is 9-9-9-24. You can look up what that means, but once you know, it is easy enough to see where to enter it into the BIOS, and with this motherboard, when the RAM is on Auto (as it is by default) the actual value it is using is printed to the left in grey lettering. It is a fairly easy process to make sure the manually entered number matches the number displayed. Once that was done, it was back to Windows and CPU-Z to verify the configuration.


Next, I went back into the BIOS and increased the multiplier to 20.5, then explicitly set the CPU voltage to 1.4 (I have CPU Overvolt protection on). The official range is up to 1.475, but CPU-Z frequently shows it well over that without any complaints from the MB when the system is under a heavy load.

I picked those two numbers based on the results from a couple of reviews. I might be able to get away with a lower CPU voltage (that means less heat and less wear and tear on the CPU). But so far the system seems stable at those settings, and I may drive the multiplier up farther yet.

But, now, with very little work, I have a core speed of 4109 (4.1GHz), and the memory operating at its rated 1333 MHz. I haven't tinkered with the bus speed at all, and I could do that too. The trick with that is to up the bus speed a bit, then, when it becomes unstable, up the North Bridge voltage.

I should pause here and point out that upping voltages and speeds has the potential to put extra wear on your system. It might not last as long. And the secret to overclocking is not to max out everything, but to increase performance to a suitable stable point. I appear to be there, at least for now.

I ran a Passmark performance test and got 7903 for the CPU. This page give you a sense of where that fits. It is well above the Intel i7-975 which comes in at 7035 with a price of $1044 (yeah, that's just the cost of the CPU).

Not a bad showing for a CPU that cost around $200. I'll take it.

So far, the air coming out of the case is nice and cool....CPU temps with the H70 cooler are in the 30C range......nice and cool. Maybe, if I drive the multiplier up a little farther, I'll be able to roast hot dogs over the case, but do I really want to do that? No, that's what the BBQ is for...... :)

Think about it. Six cores, each running at 4.1 GHz........

I processed the pics for the last post in Photoshop from RAW images taken with my DSLR. All I can say is 'Wow'......what was once slow is now so fast, I almost don't notice something happened. I didn't have time to go get a cup of coffee before, but I certainly had time to yawn. Now, if I blink, there's a good chance I'll miss it.

Welcome to The World of Hexaputing.....


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