Kingston DDR2-1066 HyperX voltage

[kaldek]

Hi folks,

I have just purchased a kit of 2 x 2GB Kingston DDR2-1066 (PC-8500) HyperX modules and have a couple of questions about ramping it up to its full speed in consideration of taking my Core2 E8400 to 3.6ghz.

First, my motherboard is an Asus P5KPL/1600 with fairly restrictive overclocking capabilities. It even has memory voltage "auto" settings which worry me. The motherboard also sees the memory as DDR2-800 and doesn't offer me much flexibility with setting the memory frequency.

My memory kit says that it is designed for 2.2 volts at 533mhz. I am worried that if I overclock my system to a 500mhz memory frequency (I can't set 1066 in the BIOS, only 667, 800, 1000, and 1200 are available to me) and leave the memory voltage to 'auto' it will push more than 2.2 volts through the DIMMs and fry them.

Would I be best off setting all my overclock settings to manual, and use the following:

CPU FSB: 400Mhz
Memory frequency: 1000mhz (500mhz x2)

What should I do with the memory voltage - keep it low (under 2 volts, say) and slowly work my way up? What voltage is likely to nuke these modules anyway?

As a side note, if I leave the memory to its stock 400mhz frequency and overclock the CPU to 3.6ghz, the memory frequency goes to 480mhz by itself....almost as if there is some stupid logic in the motherboard's overclocking capabilities.

[Lsdmeasap]

You can change the memory voltage from Auto, to whatever you want.

2.2V is just what is allowed, not always what is needed. I'd say start with 2.1V as they are likely to work fine with that amount. Be sure you also set your own Northbridge voltage (MCH) to 1.2-1.24 for 4GB

[kaldek]

Bizarre - I just overclocked the CPU to 400Mhz FSB (3.6Ghz core), forced the memory to 667Mhz (333x2)....and now CPUID tells me my memory is running at 400mhz, 1:1 (in consideration of it actually being 800mhz).

WTF?! If I actually set it to 1000Mhz it would probably blow up in my face based on that fact. I'm going to set it to 800Mhz now - I bet it ends up running at over 500mhz, resulting in a "real" memory clock speed of 1,000mhz.

Lucky it's rated to 1066mhz....

[Lsdmeasap]

It just says 667, because that would be with the default FSB. It is the x2 you are really choosing which is 2x FSB which would be 800. Looks normal to me, that setting is simply the 2.00 or 1:1 setting, next one up would be 2.40 or 5:6

[kaldek]

It just says 667, because that would be with the default FSB. It is the x2 you are really choosing which is 2x FSB which would be 800. Looks normal to me, that setting is simply the 2.00 or 1:1 setting, next one up would be 2.40 or 5:6

Riiight, I get you. So when I select "667" they really mean "1:1" and when I select "800" it really means "5:6". I bet "1000" means "2:3".

So basically, a pretty crap mobo for O/C work then. If I set my memory speed to 1000, it would actually end up going to 1,200mhz. Not helpful.

[Lsdmeasap]

Ya it would be:
1:1
5:6
5:8
1:2

[kaldek]

Ah well, I must admit I didn't go looking for an overclocker's board when I picked this one up, so I really can't complaint too much.

After setting my Vcore to "+50mV", the FSB bus to "400", the memory speed to "800", and my memory voltage to 2.1 volts, I have a stable 3.6Ghz E8400 with 960mhz memory. I suppose I could try to push the memory to 1,200mhz, but meh.

[Lsdmeasap]

If you have good cooling then you are not doing your 8400 justice, take it to 4Ghz and let it be happy