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BIOS settings for old hardware mix and match


Junior Member
Apr 20, 2017
Trying to put a quick computer together for my mother from some old parts I've got lying around, and I've forgotten so much about how this works it's been so many years since I've done it.

I've got an Asus P5Q motherboard with an Intel Core 2 Quad Q6600 2.4 Ghz CPU. Originally this board had two sticks of cheap Kingston DDR2-667 memory, but I'm trying to upgrade that to DDR2-800.

I have two ram kits kicking around, one of which I pinched from an Asus P5B Deluxe motherboard.
Kit one: Kingston HyperX 2G PC2-6400
Kit two: Patriot Viper Extreme 4G PC2-6400
For the Patriot memory, mine looks identical to the picture on NCIX, except the sticker has 2.1 volts instead of the 2.2 shown there.


1) Which motherboard to use? Between the Asus P5B Deluxe, and the Asus P5Q, the P5Q seems to be the consensus from every thread I can find for a Quad core CPU due to the more mature P45 chipset. This question is more or less settled, but chime in if you disagree.

2) By default, sticking in all four dimms of the DDR2-800, the motherboard downclocks the ram to 667. I can enter the bios settings and over ride that, setting it to 800 mhz along with the 4-4-4-12 timings settings but the CPU remains at 2.4ghz. From searching, apparently this CPU is unlocked and clocking it at the same rate as the ram should be trivial but the number of configurable settings is staggering and I'm completely lost. The goal here is not a vast overclock, but matching bus speed and multiplier to have this ram run at it's peak along with the processor.

3) Having all four dimms of DDR2-800 in the machine, the post only reports 5GBs of memory detected instead of 6. I've found other threads discussing similar problems, but with different answers for everything. Some suggest it has to do with a memory mapper settings, others suggest insufficient memory voltage. Not sure what to do here.

Some notes:
-Using a 400watt power supply
-Updated the MB bios to the latest version
-The voltage between the ram kits is slightly different. The Patriot is listed at 2.1 volts.
The Kingston, according to it's PDF, operates at different voltages depending on the timing values set. 4-4-4-12 @ 2.0 volts, which I'm hoping will be fine to be pushed up the .1

I've been reading countless threads all over the net for hours now, and I can't seem to get a matching search phrase. I come humbly asking for help feeling somewhat defeated.
Thank you kindly for your time. :)


Elite Member
Sep 1, 2002
1. The P5Q is probably the board to have, if for nothing else than the fact that it is newer and has the best chance of lasting a while longer.

2. Don't bother overclocking the RAM. You want stability, and RAM overclock doesn't help that much with these.

3. As the memory controller requires dual channel, it sounds like nothing more than memory sticks in the wrong slots. The manual states "the system maps the total size of the lower-sized channel to the dual channel configuration." I would suggest the 4 GB slicks for slots A1 and B1, the 2 GB sticks for A2 and B2. And honestry, if it comes down to it, I don't know that the 2 GB sticks would even be necessary.

4 (The bonus answer). If you have a good cpu cooler and the chip is a G0 stepping, I would definitely recommend a mild overclock in order for that chip to last her a while. If the answer isn't yes to both questions, don't worry about it.