790i reference board volt mods (UNCONFIRMED mods) >> work in progress

[Deanzo]

I've got an odd one for you guys.

Since doing the mods I can't run over 1.6 volts
Any ideas why this would be ? (if it matters I'm under LN2 doing this)

I only tested the mods at around 1.4 volts and all seemed fine.

Before I did the mods I could hit 6Ghz @ 1.96 volts one core easy http://valid.x86-secret.com/show_oc.php?id=369183 but I had real issue being SPI stable over 5714Mhz (my cpu is good for 5.9) so a vdroop mod was in order.

@ Kabauterman, what were you issues under the cold ?


Edit:

Just tried around 0c, same issue.
Though you can see the vdroop mod is working.

[dinos22]

interesting
try backing off on vdroop somewhat

[3oh6]

quite interesting deanzo. i have been under a single stage for over a month now with the mods done and never had any issues what so ever. of course, my temps haven't gone below -40C on the CPU. i might grab some dry ice early next week to see if i can get this E8500 up past 5.3GHz so i might be able to report on slightly lower temps then.

[Gautam]

Dean, your droop mod is overdone, increase its resistance. I saw from graphs you posted earlier that your vcore was increasing under load. There's a sense circuit tied somewhere to the vreg (can't remember where) which makes it go beserk if the voltage it receives is higher than what it thinks it should be. You have to let there be some droop, and annoyingly enough, you have to allow more the more vcore you want, since it seems to me that the board deliberately has heavy vdrop at higher vcores. The way I have it set now, 1.9v usually results in the board not powering up, but I never need that much...you will though.

Right now I've got about 1K on the dot across the vdroop resistor, IIRC that should mean that my VR is set to about 2K.

Furthermore, this actually varies board to board. Some boards let you have more aggressive vdroop mods than others, go figure.

[Deanzo]

I see,

Thanks G, I'll give that a try tonight

[Deanzo]

More odd stuff in Kiwi land

I'll do the best I can to tell you what I see.

First thing I did was to increase the resistance by one full turn, and that didn't help.
I did another full turn and the board wouldn't post, as well as every turn for the next 22.
Lower the resistance by 23/24 turns and the board would post again

At this point I took the vDroop mod off to see what would happen..And that = No post no matter what

Then I though...(Hold on, I lowered the resistance on the vCore mod when I did it so windoz would be the same as bios) When I did that it took alot of turns before I saw anything in windows, but I didn't think anything of it as it worked in the end.
So before doing anything else I increase the resistance by lots of turns (sorry I didn't count them) when I tried to boot this time it worked.
But, I still had 1.5v set in the bios. But when I opened CPUZ it read 1.67
Re-booted and had a look at the read out in bios and saw the same thing!

This is very odd to me as when I had both mods on the board, I only lowered the resistance so it would be the same as set in the bios (but again this took alot of turns)
At this point I took the vCore mod off and everything was fine with the board. And the 50K VR was sitting @ 40K. The VR never went higher than 45k to start with and is still like that.

So this would mean at 40K it was setting the vcore .2v higher than bios, if you take bios drop into account (.167 in windoz)
After taking off the vDroop mod, not posting must have been OVP kicking in.

I have no idea why the vDroop mod was letting it post/boot and why the readings were not the same, but maybe one of you guys know.

But imo (and with out the vDroop) 50K VR is far to low for this XFX board.

Now if we re-call zbogorgon post, and he was using an XFX board as well.
A 200K would be the way I'd go, if I was to re-do it. But I don't have a 100 or 200K VR here to test it.

Odd Yes ? Dino, you may want to add something about this and XFX boards in your first post untill we know more.



Next up, I put the vDroop mod back on.

This time it was set to just over 9K to start with, with 1.5 set in the bios.

It booted fine and read 1.465 in windoz and 1.417 under load.

With one full turn of the VR, that went to 1.465 --> 1.424

Another full turn 1.465 --> 1.431

And another 1.471 --> 1.449 (Tested all the way to 1.87v)

And the next one gave me 1.480 --> 1.480 (this will not post/boot/work over 1.57v)

[DON3]

VCORE & VDROOP MODS

Tomorrow, I will try the pencil vdroop mod...

Will my XFX be damaged? I hope not...

[dinos22]

pencil mod didn't work for me and others

maybe a waste of time

i have a warning there regarding VRs used

[aussie-revhead]

Hi Dino and guys , I came here looking for a vdroop mod as Im loosing 0.1v from bios to loaded in windows , it makes 1.37v loaded into 1.47 in bios . I saw above that the vdroop mod has to be tuned , is this better than LLC on asus mobos as vcore wont spike when load is reduced ?

Im going to be very careful with this qx as its too dear for me to go buy another if I nuke it .

Im also concerned that changes in bios do not seem to make any difference in windows ie you go up one or two steps in bios and windows voltage shows the same , is this common ? Or is this a part of the droop problem ?

Its priming at 4GHz 1.37v loaded , its not a very low VID model (1.275v), so Im pretty happy with that.

[DON3]

So dinos22, there is no pencil mod for this board, right?

EDIT: What will happen if i try this pencil mod?

[RLM]

EDIT: What will happen if i try this pencil mod?

Not a lot.

RLM

[DON3]

Like dinos22 said, pencil mod doesn't work!

[aussie-revhead]

RLM - is 9.29s 32m wprime good ? Thats at 4511 MHz , unlinked , untweaked , just testing .

[DON3]

The only solution for vdroop is soldering a 50K VR, right? It's better to forget the pencil mod...

[T_M]

Just grabbed an XFX, and measuring default vcore resistance = 44k.
So maybe Zborgon was right (for XFX board) and 50k was too low and tripped his OVP.
Im going to run the board up now on air, check some things, then perform vcore = 200k VR, vdroop = 10k VR.
Will report back later.

[Deanzo]

This is a learn as I go, kind of thing.

I changed the mods on my XFX board, so I could try other VR's more easily.

I have now tried a 200 & 100K VR, when I lower the resistance I can see the vcore raise when the VR get's to 83K.

[dinos22]

i used a 50K today for droop mod

had to get it down to 1.5K to get droop easing

benched a bit but board didn't like anything more than 10x multi on a quad

later put my E8500

now i have a dead CPU and a dead board so go figure

[T_M]

Deanzo, whats your default resistance to ground on that XFX?

[RLM]

now i have a dead CPU and a dead board so go figure

Sh*t man, bad luck. Is that your second 790i?

RLM

[Alexxx650]

Perfectly works vDroop Mod.
Was 2.3k all over again after vDroop became 1.99k.


I am happy

[dinos22]

Sh*t man, bad luck. Is that your second 790i?

RLM

first one is alive
it ended up being a PSU problem

but replacement board that i put a vdroop mod on is definitely dead as a door nail

[Gunslinger]

Anyone in the US willing to do Vdrop & Vdroop for me? Drop me a PM if you would be interested.

[Delirious.]

call someone locally to do it professionally. Someone who does work under a microscope to make sure it can be done right and not mess up the resistor.

50K resistors can be found cheap at frys.

[Gunslinger]

I've looked locally, but have not had any luck. Was hoping one of the experienced people here would be willing to do it for the price of the parts and their time. I have zero soldering skills, or equipment.
No fry's in North Alababma, only BBQ stands and a bazillion mexican restaurants.

[Delirious.]

I might see what the 790i FTW would come out as in price. It will have the vdroop correction in the bios. I could sell you mine and keep it registed for you in case anything went wrong. just thought I'd throw it out.