Need some help with an X850 Vmod

[Codeman05]

We are about to vmod a friends X850pro to see what we can get out of it.
It is currently watercooled and running at 550x600 at 41c load, so we're curious to see what upping the voltage to 1.6-1.65v will do for the core.

I've been reading the guide on Tech Power Up: here (http://www.techpowerup.com/articles//overclocking/voltmods/112/4)

but its doing a better job of complicated it then clearing things up for me for some reason.

Basically, my understanding after reading the article is that using a 10k Ohm VR on the solder points for where R1597 used to be...nets only a .04v increase on the vcore? That doesn't seem right, am I misreading this guide?

All I really need to know is which VR do I need to get to 1.7 on the Vcore.
I've seen a few people using 20k VRs...which would you recommend

Thanks

[Jimbo Mahoney]

Use a 10k on the core.

That's what I'm using on my X850XT (non PE).

Using a 20k will just give you a slightly lower voltage when it's at full resistance, and you'll have slightly less control when you get up to the 1.7v range.

I think using a 10k pot only boosts the voltage 1.45 - 1.5 when at max resistance anyway.

HTH?

EDIT - Re-reading your post, it seems you think a higher resistance gives a higher Vcore? Sorry if you realise that's not how it works, but turning DOWN the resistance INCREASES the voltage supplied. PLEASE make sure you have your resistance at MAX when you first turn on the PC after the voltmod!!!!!

[Codeman05]

yes, I think I worded that bad, I do realize the the lower the resistance increases the voltage.

Ok so I think I understand what they mean now. The 10k at max R will give a .05 boost (up to 1.45-1.5), but you can then increase that by lowering the R. I just read it as the most you could gain was .05.

Did you also do the "IGPU" mod (thought this used to be called something else). I didn't have to on the x800, but they make it sound like its nessissary on the x850s

Thanks for all the info! :toast:

[runmc]

You don't have to do the IGPU mod unless you plan on upping volts to 1.8 +

[Codeman05]

good to hear, thanks

[Codeman05]

well the mod went great, now running at 657x610...in addition, we were able to unlock the cards pipes with a simple bios flash!! So for about $200 (got it used), he now has a X850 xt, not to shabby