BIOS
NVIDIA's designed the nForce3 250Gb to appeal to the enthusiast. That's typified by the ability to lock AGP/PCI buses. Running at much over the stock 200MHz driven clock demands locked buses - it's all too easy to lose an installation to an overclocked bus, be it PATA or SATA.
The main configuration screen of Chaintech's AwardBIOS. Driven clock frequencies range from 200-400MHz. It's annoying a desired clock speed cannot be inputted manually. Cycling through each one is a time-consuming affair. By specifying a discrete AGP clock Chaintech implies the ability to lock or manipulate the bus independent of the driven clock. We have to infer that PCI bus speeds are running at 1/2 of AGP. This is all well and good, but Chaintech doesn't provide the user with multiplier adjustment or Cool'n'Quiet technology. S754 CPUs have, in comparison to Intel's CPUs, limited overclocking potential. It's rare to see a driven clock of more than, say, 230MHz, on air, without resorting to changing multipliers. That's why the absence of such a control is perplexing, as it effectively limits driven clock speeds. Not good, especially if you have PC4000+ RAM at your disposal.
Voltages are better. CPU's ranges from 1.45 - 1.7v, AGP's from 1.6v - 2.2v, DDR's from 2.6v - 2.9v, and the chipset's from 1.6v - 1.9v.
nForce3 250 uses a maximum memory clock to limit DDR speeds. The CPU's DRAM controller is a divisor of on-chip speeds, so maximum memory speeds are the closest divisor below the rated speed. For a 2.2GHz Athlon 64 Model 3400+ a divisor of /10 is perfect for DDR400 memory (200MHz). Max memory clock for 166MHz requires a divisor of 14 (2200/14 = 157.14MHz). Similarly, higher divisors are used to limit the controller to a maximum memory clock of 133MHz. We were able to use our regular 2-2-2-6 latencies for formal benchmarking.
A HT frequency of 4x (800MHz) is proof enough that this is a working nForce3 250 board.
A bizarre trait of this BIOS is the inability to toggle the functions of discrete chips. There's no audio, FireWire or GbE control whatsoever. Further, there doesn't seem to be any way of turning the features off, if need by, via onboard jumpers. It's rare to see this kind of setup.
CPU temperature is reported around 5c higher than on other boards. The ZNF3-250 has a strong CPU voltage line. DDR voltage, however, tended to hover at around 0.05v below what's inputted. There' no fancy fan control, a la ABIT and ASUS, and there's no advanced features such as saving set BIOS configurations to memory or on-the-fly overclocking. Chaintech really does need to release an updated BIOS that at least allows for multiplier selection. Without it, really, there's little point in having locked buses.
