PSP test: Paint Shop Pro image emboss operation on huge image under Windows 95.
|66/66/300||57.7 fps||7.9 sec|
|66/100/300||62.9 fps||7.6 sec|
|100/100/300||65.3 fps||7.3 sec|
|66/83/375||67.2 fps||Not attempted|
|83/83/375||71 fps||Not attempted|
|100/100/350||72.5 fps||6.4 sec|
The AMD K6-266 and faster CPUs are good overclockers because they use a new fabrication technique. The K6-233 is not as good an overclocking bet, although some can run at 250 or even 262.5.
My K6-300 has been running almost continuously at 300MHz with its external bus overclocked to 100MHz since early July 1998 with no problems. At 350MHz the heat sink gets only slightly warm to the touch and I've played Quake for hours at a time with no crashes or weird behavior.
I completed the timedemo test with Quake at 375 MHz, but it locked up or had a page fault after about five minutes. Clearly the CPU was heating up too much.
I've connected my turbo button to one of the multiplier jumpers so I can switch between 300 and 350 MHz. The motherboard doesn't change the setting on the fly. I have to punch the button and then restart the computer.
These results show that this motherboard's ability to run the CPU bus (and its one meg L2 cache, I assume) faster than main memory gets you 2/3 of the performance boost of having PC100 memory. If you already have lots of 66MHz memory, this motherboard lets you keep using it with very little reduction in performance. But, if you need to buy new memory, I'd recommend getting PC100 memory since it isn't much more expensive and will probably save you from having to buy new memory for your next motherboard upgrade.
The VA503+ manual tells you how to set the jumpers, but it doesn't tell you exactly what the jumpers do. Those of us who want to push our systems to their limits need this information. Here's what they left out.
The motherboard has 4 speeds you can set:
On all the 3 pin jumpers, pin 1 is the pin closest to the thick white line on the motherboard. In my tables, "1-2" and "2-3" mean the jumper is on those two pins.
The CLK1, CLK2, and CLK3 jumpers set the CPU external bus speed from 60MHz to 124MHz. Many of these settings are undocumented.
|CPU External Bus Speed|
The FREQ1, FREQ2, and FREQ3 jumpers set what the CPU external bus speed is multiplied by to get the CPU internal speed. All of these are official, documented settings.
|CPU External to Internal Multiplier|
The SDRAM1 and CLK4 jumpers set whether the memory bus speed is set to the AGP bus speed or the CPU external speed. This allows you, for example, to run your CPU bus at 100MHz and your memory bus at 66MHz.
|2-3||1-2||Memory=CPU external bus|
The SDRAM2 and SDRAM3 jumpers select what the CPU external bus is divided by to generate the PCI bus. The PCI bus is supposed to be 33.3MHz, but can be run faster if your PCI cards can handle it. For example, if you're running the CPU external bus at 100MHz you would normally set the PCI bus to divide by 3. If the CPU external bus is at 75MHz, you can set the PCI bus to 75/2.5=30 or 75/2=37.5. The AGP bus is always twice the PCI bus. The divide by 2.5 setting is undocumented and may not work on all VA503+ motherboards.
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