Intel P45 will be a hard candy

Posted by admin

May 14, 2008

It seems like one has to read new manuals very carefully before writing a review about the Intel’s next generation P45 Chipset because Intel has made overclocking more complicated than ever before. Overclocking has been progressively getting more difficult since the 975X chipset was introduced, but it wasn’t until more recently with P965 and P35 that more advanced options have been released by Intel as the antiquated front side bus runs out of steam.

If you want to buy and overclock on an Intel P45 board (or X48, X38 and P35 for that matter), Leach believes that you must learn how to use:

GTL Reference Voltages
CPU VTT and its relation to GTLs
Clock Skews
CPU PLL Voltages

This is because we’ve reached such a stage with the front side bus that the frequencies are getting easily out of sync. You can’t just throw voltage at things any more – that will only get you so far.

It’s a case of spending a lot of time increasing the CPU VTT (not over 1.35V – you’ll kill the processor) and CPU PLL (not over 1.7V, because again you’ll kill your processor) and tweaking the GTL Reference voltages for the CPU and North bridge to be around 61-63 percent of VTT for 45nm processors and 67 percent for 65nm.

This is particularly noteworthy with quad-core processors because, if you’re finding core two and three drop off under Prime95 load, it’s down to the fact that the two CPU dies are not identical and while core one and four can hit the FSB you’ve set, cores two and three are having trouble. Tweaking the GTL can sometimes give them better stability.

Leach even went as far as to say you’ve got to find points on the board and check the actual voltages with a multimeter, because we’re talking some extremely minute changes and if there are elements of vDrop from the board or vDroop when the CPU loads the BIOS can be inaccurate.

Next you HAVE to play with the clock skews – MSI will have these on its P45 boards, Asus has them on its current X38 and X48 boards, while both DFI and Gigabyte also have them on their X48 boards. Basically as the data has to jump from the front side bus domain to the memory domain this window becomes smaller and prone to more jitter, the faster you increase either the FSB or memory frequencies and timings. By adjusting the skew you can realign these clock signals and suddenly stability should return again – a good motherboard will have less jitter in its signal generation and finer skew adjustments than one that’s not as good.

The kicker that this is a completely blind art – you’ve quite literally got to sit there for hours and tweak the nuts off the board trying combinations of GTL and Skew settings until you find something that works. To make matters worse as soon as you change the FSB, memory timings, the CPU (no two CPUs are identical, even if you buy a “Q6600 G0”), the memory sticks (there are different tolerances between batches of the same product, never mind different products!), update the BIOS, or even if you’re using the same motherboard as someone else there’s no guarantee that one set of settings will work on another board.

So take a deep breath and start searching and reading. Good luck to u all!

Internet