X-bit labs

ABIT KV7 Mainboard on VIA KT600 Chipset Review (page 6)

Category: Mainboards

by Grigoriy Gubankov

[ 11/25/2003 | 11:19 PM ]

We are now approaching the Advanced Chipset Features page with two interesting subsections: DRAM Timing Control and AGP & P2P Bridge Timing Control. Let’s go into the first one first:

It’s clear this BIOS Setup subsection offers us wide opportunities for the memory subsystem fine-tuning. We can select the operational frequency of the memory (DRAM Clock). ABIT followed the example of some manufacturers who offer a menu of “133MHz”, “166MHz” and “200MHz” rather than a list of divisors.

I said that numerous times and I say it again. This way you will have some problems at overclocking: the FSB and memory busses being set asynchronously, you will have to spend some time thinking about the memory frequency corresponding to this FSB clock-rate, because the divisor is never shown! Moreover, you cannot see the true memory frequency during the POST procedure. Actually, I think the best way of selecting the memory frequency should be implemented as a simple selection of the divisor, while the BIOS Setup showed the resulting memory frequency (in brackets, for example). Such a system is employed in BIOS Setups of many mainboards, why ABIT went the other way? Maybe the company has a different notion of what is better for the user.

Anyway, let’s move to the DRAM Timing Control page. You can choose one of the memory timing presets: by SPD, Turbo and Ultra (regrettably, the BIOS Setup never tells which exactly timings are selected when you choose a preset). Of course, it is possible to adjust the timings manually.

I won’t dwell upon the next four parameters. Three of them refer to the internal latencies of the chipset North Bridge and comply with the rule “the smaller the value, the faster and less stable the system becomes”. The search for the stable configuration is much relieved by each of the parameters having only two possible values. As far as I know, only the Command Rate option significantly influences the overall performance, although this statement needs more evidence. By the way, none of the KT600-based mainboards we tested (including the ABIT KV7) could work at Command Rate = 1T if the memory frequency was set to 200MHz (400MHz DDR). This seems to be a peculiarity of the chipset.

The last but one option, DDR DQS Input Delay, is curious enough. It is of no exceptional value (I confess I don’t quite understand its actual meaning as well as that of the last option), but its effect is surprising. If you set this option to Auto in the Input Delay Value column, the value as selected by the BIOS is shown. There is nothing extraordinary about it. But if you try to move the cursor “in the neighborhood” of this option, its value somehow starts to change. It seems like the value depends on the number of strikes on the cursor keys. :)

Now, we are in the AGP & P2P Bridge Timing Control section of the BIOS Setup. There is no need to describe each of the options in detail. I just want to admit that the flexibility of the settings is enough to satisfy most of the users who want to “play” with fine AGP settings.