Overclocking the inexpensive AMD TBred-B Duron
Standard disclaimer: the author assumes no responsibilities if you damage your computer, burn down your house or the sky falls on your head, as a result of this article. And as usual, YMMV (Your Mileage May Vary).
AcknowledgmentsAll the overclocking techniques I'll use here have been perfected before by others, so really I am just "standing on the shoulders of giants". To name a few people I have met at OCWorkbench: my thanks first to Bluetooth, Eversor, Grumpy, Gortok, RayvenX, Bismark, Europe and many others.
Introduction: what's a TBred-B Duron?AMD nowadays manufactures two different models of its K7 core:
Because of their smaller die size, TBred-Bs cost less to manufacture, and so AMD have been selling them as their "value" line, recently rebranded to Sempron. But AMD also have an even cheaper brand of microprocessors, the Duron line. These are also based on TBred-B cores, but have had 3/4 of their L2 cache disabled, either because the die was in part defective, or simply AMD didn't bother testing all the L2 cache; these TBred-B based Durons have 128kB L1 cache, just like all K7 microprocessors, but only 64kB of L2 cache.
How much does that affect performance? There is no clear answer to that question, because cache size has different effects on different programs. One thing is sure, Durons are in general slower than normal TBred-Bs, and TBred-Bs are slower than Bartons.
The sample in the picture has the core still covered with a thin layer of thermal compound. The 0403 denotes the year and week it was manufactured (third week, 2004). The 1600 denotes the speed rating, which in this case is 1600MHz (12x133MHz).
Durons are tested and guaranteed to work with a 133MHz FSB with a 1.5V supply voltage. Any higher FSB means we are entering overclocking territory. Normal TBred-B cores, on the other hand, like those used in Sempron CPUs, are specified to work with a 166MHz FSB. And TBred-B cores are known to handle voltages up to 1.85V with adequate cooling. This raises interesting overclocking possibilities...
The AMD Duron is the least expensive x86 CPU found in retail right now.
This particular sample seen above cost me 38 Euros, with taxes. It
not make sense to use it with a 200 Euros mainboard! I have been using
the ASROCK K7S8X line of
mainboards for some time now and they make a perfect match to the
Durons: stable, simple to setup and inexpensive. And what's best, there
is a great
support forum for ASROCK mainboards at OCWorkbench.com!
There are three similar models in the ASROCK K7S8X line, with slightly different features:
First step: 2GHz at 1.65V VcoreThe first test is to simply change the FSB_SEL jumpers on the mainboard to set the FSB to 333MHz, and set an option in the BIOS to raise the voltage by 5%. But wait, 1.5V + 5%, equals 1.575V! Like this:
Well, I have found that at 2GHz, most TBred-B Durons would require 1.65V to be 100% stable. Your mileage may vary, but raising the voltage is as easy as inserting two small pieces of wire in the CPU socket before you lock the CPU in place. Easy, reversible, does not require a soldering iron or any special skills, and 100% safe. Just make sure you put the wires in the correct holes (as shown in red below) or you could damage your CPU:
The appropriate socket holes to insert jumpers can be found at the excellent Interactive Pin-Mod Guide. I recommend choosing a 1.675 target voltage which requires just two very small pieces of wire, as shown above. The wire must be really thin (like a hair, almost) and the small u-shaped jumpers are very, very small, like this:
I found another article with some good shots of the small bits of wire here.
The result is this:
These Durons run quite cool at 2.0GHz at 1.65V Vcore, so an inexpensive heatsink/fan is OK. Note that I have used either PC2700 (for the 333MHz FSB tests) or PC3200 (for the 400MHz FSB tests) noname 256 and 512MB DDR SDRAM DIMMs. The power supply is an inexpensive 400W standard model with a single exhaust fan. As shown this mod will work fine on the SiS 746-based K7S8X with an official BIOS.
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