DFI LANParty UT P35-T2R

[eva2000]

Yeah increasing CPU PLL on both Asus P35 and DFI P35 board helps max FSB but each cpu responds differently to CPU PLL to FSB scaling.

i.e. i'm testing 2x E6850 L723A347 retail cpus on Asus Blitz Formula

#1 - max 485-487FSB and doesn't respond much to CPU PLL upto 1.8v

#2 - max 523-525FSB at 1.5v CPU PLL and at 1.7v CPU PLL 530FSB and 1.8v CPU PLL 533-535FSB.

Both cpus on Corsair Nautilus 500 water.

For both Asus and DFI P35, try looping memtest86+ v1.70 test #7 to also test for max FSB.. it will freeze and/or not reboot on memtest86 exit if you hit an FSB wall.

[freecableguy]

The only reason question I have regarding CPU PLL voltage is in regard to maximum safe voltage. Can some on find the PLL chip and lookup the datasheet and tell us the manufacturer's recommended VCC range? I willing to bet it's well below the maximum supplied by the board...maybe a phone call to the local office to talk with an engineer would be in order. If there's not a high potential for IC failure as a result of the out-of-range VCC then I'd have a hard time not recommending to others to max this setting as part of their routine for finding max FSB (not that I think max FSB is really that important anyway).

-FCG

[Praz]

I have a hard time believing 2.15V (which is the max on this board) isn't detrimental to the chip when default is 1.55V. Might be ok for short benching sessions though.

I'd like to know why it makes such a difference. It behaves like some type of driving strength adjustment for the cpu. The results achieved with the increased voltage is definitely processor dependent.

[Raja]

Originally Posted by freecableguy

CPU PLL voltage is nothing more than VCC for the PLL chip that provides the reference frequency for the CPU FSB, PCI, etc. I'm not clear as to why this changes anything, although some people claim it gives them 2-5Mhz more just by maxing it out....go figure.

the over voltage in that case probably reduces clock jitter very slightly, 30-40mhz would sound about right for a slight jitter reduction.

Nominal volatge ranges for these types of devices used to be from 2.15-3.3v depending on part number..

Anyone got a part number there of the PLL chip so I can lookup the datasheet..?

regards
Raja

[eva2000]

not sure but Kevin/OPB's been saying for long term keep CPU PLL <1.7v

[Praz]

Loosening the Performance Level will allow a higher FSB with a lower PLL voltage. May have to increase NB and VTT voltage. This part seems processor dependent. For 24/7 it's going to be a balance of voltage and performance.

[Tony]

Thought I would add some info Jimmy at DFI was kind enough to forward to me. Kris could add this to a guide also if needed





Over the next day or so i will explain what we have here and how to use the tables.

Big thanks to Jimmy at DFI here for the info.

EDIT 1 the top table.

This table pretty much shows what happens when you leave GTL's at auto and change VTT. All the time though GTL's will show at 110,
It is recommended you follow this table manually if you choose manual as this table closely follows Intels spec's

Next table shows what bios has as options for VTT and what is actually set.

The bottom tables show the relationship of VTT and GTL...An example is setting VTT to 1.2 and GTL to 115 will give 0.86V but with VTT at 1.5V 115 gives 1.05V

[Praz]

All voltages except processor and memory at default values.

[Tony]

I really do feel the board is capable of 600+fsb the issue is the CPU's are not, kind of a shame really such a board is being held back.

The team at DFI did an awesome job though tuning this one and it will get the max from your CPU....

530FSB on default voltages is really kinda nice Praz

[Praz]

Early results do point to the cpu as being the limiting factor. Sub-zero cooling on the processor seems to be the way to reach 600+ FSB. Even then there appears to be some behind-the-scenes timing manipulation going on because the posted SuperP scores are lower then one would expect.