Power supply unit and overclocking. [56k Warning!]

PangingJr · Jul 23, 2008, 08:20 AM

let's just start this off... a few weeks ago when i first got a new motherboard, P5Q Deluxe, i stated a setup using CoolerMaster 550W and 2x1GB of RAM and C2D processor,
then i change to use 4x1 GB of RAM and C2Q processor, anyway, i have 3 new power supply units, CoolerMaster 550W, EMACS 500W and Corsair 620W,
all 3 PSUs are working okay for my overclocking, it's just the voltage requirement to support a certain clock frequency are different for each power supply unit,
well, i will not going into any more detail, so, for a couple of examples of what i'm talking about and looking for other people experienced in something similar to this...

all vDimm's is the value that are set in BIOS... testing softwares and method... ran memtest86+ #5 test for 10 passed (that's all to it, i'm not talking about a solid and stable voltage that i will actually use it).

DDR2-1066 ( 333x7.5 5:8 and 444x7.5 5:6 )

CM 550W - vDimm = 2.1 V
EMACS 500W - vDimm = 1.98V
Corsair 620W - vDimm = 2.02V

all hardware setup and rest of BIOS setup include the version of BIOS in use were the exact same, just different in power supply unit in use.

i'm not sure what is the technical reason why voltages requirement in the overclocking are different and depending on power supply unit in use,
there are more things about power supply and my overclocking that i have been noticing but i cannot going into all that now.

here's my setup for overclocking test. (it's a temporary setup since i will probably never finish it)
right now i just start with Corsair 620W...

Judas · Jul 23, 2008, 11:52 AM

interesting.

i typically try and use the coolermaster Extreme power PSU models..

the Real power ones for whatever reason, have shown a poor performance rating

PangingJr · Jul 23, 2008, 12:16 PM

that CM supply are old models i have it (still having, actually 2 more that never been used) a couple of years ago i think.
some of 3 lines start dropping volts quite a bit when system using too many drives and high overclock.

Corsair 620W has +5 line drops abit with a high overclocked and high load, +3.3 and +12 are both seems to be good and stable.

the EMACS has all three main supply lines very solid especially when the system running in a cool room, but 500W is abit too steep now.

Judas · Jul 23, 2008, 12:19 PM

yeah 500 watt is pushing it imo.

500 watt CM extreme power PSU's is what i use in all my general builds... any machine the is going to be pushed a bit more or demanding more power, i usually stick a 600 watt + higher end model such as OCZ GamerXStream or similare.

swimtech · Jul 23, 2008, 01:53 PM

I'm thinking your rams are designed to run on 2.0 - 2.1 volts (the GSkill 8500 PC1066 rams...)

It's unusual to see the amount of variation you're seeing on the voltage from the PSU on the line designed to supply the memory voltage though. The motherboard uses either the 3.3v PSU rail or the 5v PSU rail to supply a regulator on the mainboard that actually delivers power to the memory chips themselves - and we've all seen reviews of decent supplies that show those rails don't change much with regard to load up to their rated output.

That being said then, it is more likely that the issue you are having is related to mainboard memory voltage regulation than the PSU itself.

I know you've used other mainboards - did those boards, other than the P5-Q you are using now - have the same problem? If not, then you know where the problem lies...

PangingJr · Jul 23, 2008, 02:32 PM

nope, my GSkill 8500 HK kits have spec'ed and EPP for DDR2-1066 @ 2.35V,
but myself and everyone i know who uses this GSkill kit, are actually use 2.35V vDimm for ruuning it at speed of DDR2-1200 and above.

lol, anyway, not sure why you think i'm having a problem with my hardwares.
those are just something i found while experimenting my CPU and RAM overcloking with a limited hardwares i already have.

well, if from the beginning i only use 1 power supply, i would not need to try to use a different voltage settings then.
and, if i can recall, yes, this was also more or less the same with my other motherboards, i mean, not just the vDimm, but the core voltages requirement for overclocking as well.
same motherboard and CPU, RAM and etc, just a different PSU, and i mean they all can be a stable system, with a slightly different voltage settings.

right now i'm using the Corsair 620W, and overclock my CPU to 458x7.5, 5:6, DDR2-1100 (4x1GB) @ 2.08V, and pass a quick prime stress test,
when i were having the CM supply i needed 2.16V and 2.02V with the EMACS supply.
same BIOS profile in use, i only change vDimm after loading the OC profile (the overclocked profiles on each version of BIOS has been saved on a pen drive)

with the CM supply unit was in the system, i was not able to get 500FSB and at 4x1GB 5:6 DDR2-1200, and then i was able to after changing the supply to the EMACS unit.

with the Corsair 620W it seems that i'm getting less and less overclocking failed (at BIOS level) than i used to have with the other 2 supply units.

swimtech · Jul 23, 2008, 04:27 PM

Oh, you're saying you set those voltages in the bios on purpose, to experiment. I did think you were experiencing reduced measured voltages - sorry...

Interesting...

PangingJr · Jul 23, 2008, 04:54 PM

you may not notice this in Gigabyte 'cause the vDimm setting in BIOS is just different...
if you have a chance to change or swap your power supply then try lowering the volts and see.
i think it's there more or less.

as for the P5Q-D board, the vDimm can be increase by +.02 at a time.

this will be more clearer on how the different of 2.02V to 2.08 and to 2.16V

2.02V... 2.04... 2.06...2.08...2.10... 2.12...2.14... 2.16V

2.08V... 2.10... 2.12...2.14... 2.16V

2.02V... 2.04... 2.06...2.08

btw, P5Q-D's seems to overvolt Dimm voltage by +.08 V.
this's set at the board, so for BIOS set 2.02V, it's like 2.10V actual.

swimtech · Jul 24, 2008, 08:40 AM

Yeah, I can only increment the Dimm voltage by .05v increments on my board - EX38-DS4.

I've got an Antec Earthwatts 430 in the old machine, but doubt I would ever pull that to try...

I was looking at a schematic for the memory power controller chip used on mainboards, and it states that noise on the PSU memory supply rail gets coupled to the data lines because of the low impedence of the circuit. Evidently, the PSU supplies the memory voltage almost directly with little filtering, and only one or two (now advertised in the latest ASUS boards...) stages of DC regulation. In other words, the controller chip is the most complicated device in the memory power control/data bus system. The regulation of the PSU rail to memory supply voltage is very simple - apparently passing most noise/ripple on the PSU's 5 or 3.3 volt lines into the memory power/data subsystem.

This means the quality of DC on the 5 and 3.3 volt lines is fairly critical to the stability of the memory subsystem - you could be seeing the effects of this with your differing PSUs.

PangingJr · Jul 24, 2008, 01:44 PM

when more higher 12V line amp supply is in use with the P5Q-D, the board acts and overclocks my Q9300 very well,
now, the CPU PLL, FSB Termination and NB voltages can be reduce quite a bit as well.

PangingJr · Jul 24, 2008, 02:53 PM

anyway, speaking of overclocking Q9300 (a bit offtopic, forgive me),
before i got my first Q9300 i used to read this article X-bit labs - The Youngest of Yorkfields: Intel Core 2 Quad Q9300 Processor Review (page 6)
the article itself is good, but for all the voltages they uses in the overclocking,
they needed to use < CPU PLL voltage 2.0, FSB termination voltage: 1.50V, NB voltage 1.65V >, for (only) 467x7.5,
i think those are just crazy voltages.

with P45, P5Q-D, for the same clock, i needed way lower voltages than that,
the P35-DS4 don't have a CPU PLL voltage setting in BIOS, but i sense i must be using more lower CPU PLL and rest of the voltages than that too.

PangingJr · Jul 24, 2008, 11:12 PM

now, at 444x7.5 5:6 and memory runs at DDR2-1066MHz

vDimm = 1.96V
CPU PLL = 1.52
vFSB = 1.24V
vNB = 1.24V

before i couldn't not set CPU PLL less than 1.54 and vFSB less than 1.26V when overclocking this particular Q9300 on this same clock (or even below this), otherwise i didn't seem to able to get in Windows or the overclock would just hang right at BIOS level.

btw, for this particular Asus P5Q-D that i'm now using, i have to manual input almost all the required BIOS overclocking parameters, just couldn't leave them alone at Auto, otherwise the overclock would also fail right there at BIOS.
as far as i know, on this particular model board, same revision boards, some of the boards can use the Auto settings, but some cannot, and probably wouldn�t be able to overclock some certain CPU's FSB to something above 400FSB with CPU PLL, vFSB, vNB and CPU GTL Ref's parameters are left at AUTO.

swimtech · Jul 25, 2008, 07:33 AM

Quote:

Originally Posted by PangingJr

now, at 444x7.5 5:6 and memory runs at DDR2-1066MHz

vDimm = 1.96V
CPU PLL = 1.52
vFSB = 1.24V
vNB = 1.24V

before i couldn't not set CPU PLL less than 1.54 and vFSB less than 1.26V when overclocking this particular Q9300 on this same clock (or even below this), otherwise i didn't seem to able to get in Windows or the overclock would just hang right at BIOS level.

btw, for this particular Asus P5Q-D that i'm now using, i have to manual input almost all the required BIOS overclocking parameters, just couldn't leave them alone at Auto, otherwise the overclock would also fail right there at BIOS.
as far as i know, on this particular model board, same revision boards, some of the boards can use the Auto settings, but some cannot, and probably wouldn�t be able to overclock some certain CPU's FSB to something above 400FSB with CPU PLL, vFSB, vNB and CPU GTL Ref's parameters are left at AUTO.

...and this is with the Corsair PSU, correct?

PangingJr · Jul 25, 2008, 09:02 AM

yes.

and the 444x7.5 is done, for now. it's already prime95 stable for a few hours.
i'll be using this setup and the overclock setting for a week and see.

but i'm trying to get Zippy 800W supply from my friend, he's still using it right now to overclock his new EP45T-EXTREME DDR3, i love to play with that board someday lol.

PangingJr · Jul 25, 2008, 11:39 AM

now at 3.6GHz 480x7.5 5:6 and memory runs at DDR2-1152MHz

vDimm = 2.12V
CPU PLL = 1.56
vFSB = 1.32V
vNB = 1.30V

before i had to use CPU PLL 1.62, vFSB 1.36V and vNB 1.34V to got into Windows
and then ran a prime95 stable, but with the EMACS supply and vDimm was at 2.08V