Which voltage line is most important for GPU overclocking?

O

Optimummind

Gawd
Joined
Feb 11, 2004
Messages
518
I noticed that there is an inverse relationship between how far I can overclock my CPU to my GPU.

If I overclock my CPU to a high level (such as my current 2.8E to 3.5GHZ overclock), my BFG 6800GT can't be overclocked that much. In fact, with my CPU at 3.5GHZ, my 6800GT flashed into an Ultra can only go up to 434/1120MHZ. Even so, it's not 100% stable in all games.

Funny thing is all the recent games such Far Cry, Half Life 2, and Doom 3 have no trouble running my system at 434/1120 with the CPU at 3.5GHZ.

However, on Warcraft 3: TFT, which is a much older game, I get random bootkicks out of BNET games. This behavior doesn't occur in single-player campaignes. Only on BNET games do I experience this.

Using Abit's program, I noticed that my 12V gets as low as 11.4 V sometimes.

Could this be the culprit behind the inverse overclocking relationship between the CPU and the GPU? My current PSU is a Vantec Stealth 420W PSU.

Here are the specs:
(1) 3.3 V, 26A
(2) 5.0 V, 42A
(3) 12.0 V, 18A

According to Maximum PC's reviews, the Vantec Stealth did not have a PFC (Power Factor Correction) feature. Could this lack of the PFC feature coupled with its inability to maintain a close to range 12V range be the cause of my overclock limitations?

You see, with my CPU underclocked to even 3.2GHZ (still a 400MHZ overclock from stock), my BFG 6800GT can reach 440/1200 and remain stable?

What do you guys think?
 
your putting a real strain on your power supply. the video card is using the 12volt rail, 18 amps is bare minimum for the new cards.


i think you should grab a quality psu with atleast 24amps on the 12volt. something like the ocz 520watt powerstream ;)
 
I think i still hate you for being able to OC your video card higher than I can. :mad:

And i don't have an intelligent response to your question.
 
UltimateMan said:
I think i still hate you for being able to OC your video card higher than I can. :mad:

And i don't have an intelligent response to your question.
Click to expand...

Sorry. :p

But seriously, did you try overclocking your card higher again after doing a BIOS flash with an increase in the voltage?

I modified the reference nVIDIA BIOS revision v5.40.02.15.12 using HexWorkShop to change all the three voltage modes--2D, 2D/3D, and 3D--into 1.4 V.

Then I flashed the card in Windows using nVFlash v4.42.

Also keep in mind that besides getting lucky and receiving a very overclockable GT, I also have a dedicated waterloop just for the GT.

When the GT used to share the waterloop with my Koolance Exos loop, it couldn't be overclocked as high.
 
Thanks for drudging up old memories of my failed attempts @ 1.4V. SALT IN WOUNDS!

Seriously, I have tried everything, and I have found my max: 400/1.05 @ 1.3V. @ 1.4V nothing is stable...sniffle...sniffle...

Now I can only play games at crazy high settings with crazy high fps...oh wait that's a good thing! :D
 
Here's an update. I went and ordered the Antec NeoPower 480W PSU from ZipZoomFly.

The price was cheaper than Newegg's and shipping was free for a FedEx 2-day. :D

Maximum PC gave it a 10/10 score and I'm hoping to see some OC improvements. I'll keep this thread updated!
 
i have a question if its the 12 volt rail that makes everything work andyou need major amperage why not hook up a lawn tractor battery to it use the psu to charge it to 12.5 and when u game itl slowwly drain it then when u sleep itl charge back up ??? isnt that hardcore?
 
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