BIOS Features
MSI seem to be fans of AMI BIOS' and so are we. AMI BIOS v3.31a being the particular BIOS used for the 645E MAX-LRU.
FSB can be manipulated from 100 - 200Mhz in one MHz increments respectively. Strangely enough, you have to manually increase the FSB option by 1MHz at a time, you cannot simply key in the desired number.
The CPU to DRAM clock ratios can be a shade confusing to say the least. I've sought to draw up a simple table to illustrate the various frequencies possible.
|
FSB |
PCI Bus Speed |
FSB:PCI Divider |
FSB:Mem Ratios |
Possible memory speeds |
| 100 - 132 Mhz | 33.3 - 44Mhz | 3:1 | 1:1 | 100 - 132Mhz |
| " | " | " | 3:4 | 133 - 176Mhz |
| " | " | " | 3:5 | 167 - 220Mhz |
| 133 - 165Mhz | 33.3 - 41.25Mhz | 4:1 | 4:3 | 100 - 124Mhz |
| " | " | " | 1:1 | 133 - 165Mhz |
| " | " | " | 4:5 | 166 - 206Mhz |
| 166 - 200Mhz | 33.2 - 40Mhz | 5:1 ? | 1:1 | 166 - 200Mhz |
At every FSB speed, you are presented with a range of FSB:Memory dividers. Running the divider with a 3:4 ratio at 100FSB gives you a memory speed of PC2100 (or 133MHz), running the 3:5 gives a memory running speed of 167MHz or PC2700. As the 645E Max-LRU has official 533FSB support, we see a 1:1 FSB:PCI divider. Memory options allow for PC2700 memory to be used if you choose the 4:5 divider. Memory can only be run synchronously to the FSB if you manage to hit 166FSB or above. It's is kind of confusing but does make sense if you take a little time to study it.
CPU Vcore can be adjusted from 1.475v to 1.6v in 0.025v increments, this is rather disappointing from an overclocking point of view, as we've seen a number of motherboards offer up to 1.85v Vcore without having to modify the motherboard or CPU in any way. We really do hope that higher voltages are incorporated with future BIOS revisions.
Unlike the present MSI 645 Ultra, the 645 Max offers DRAM voltage adjustment, almost a necessity if you're using PC2700 memory. 2.5v to 2.8v is available in 0.1v increments.
Memory timings can be tweaked but not to the extent that some of us would desire. You're given the choice of running at either CAS2.5 or CAS2, and are able to manipulate general memory timings to 'Safe', 'Normal', 'Fast', 'Turbo' and 'Ultra' . You are also given the option of running the performance-enhancing 1T memory command. We see an option that allows you to set the host to memory (incorrectly spelt) latency to fast, this, however, resulted in the system booting incorrectly.
Here we see the range of onboard options adjustable from within BIOS. These emobdy the MSI 645E Max-LRU, so switching them off would be illogical, still, the option is present if required. The usual gamut of options are present in the form of hardware monitoring, AGP, device and power management respectively.
We see adequate provision for running at 133FSB with the use of appropriate dividers. Strangely, we've seen other SiS645DX motherboards boast a 3:6 FSB:Memory ratio at default speeds. In layman's terms, this means that DDR400 memory would be supported out-of-the-box. This isn't the case with the 645E Max-LRU, we're sure a BIOS revision could cure that. As DDR400 is a rarity with appropriately premium prices, it has little practical value, this will change as production is increased, however.
The BIOS options are comprehensive enough although we're slightly disappointed with the 1.60v maximum CPU voltage on offer, this seems somewhat conservative in the current climate as an increasing number of motherboards offer 1.85v by default.
