7900GT Voltmod-2

[CompGeek]

You guys will never believe what the problem was.

I took that ramsink off my mosfets and everything returned to normal. :S

Now I may have a PSU problem though. I started 06 @ 750/900 and when I got back about 2 mins later my PC was off.

[Roger_D25]

CompGeek,
Which mosfets did you remove the heatsink from? Also do you have ramsinks on the memory IC's? Sometimes if airflow is insufficiant ramsinks and heatsinks can actually work against the cooling of whatever their connected to. I'd like to know because I have heatsinks on my memory IC's, as well as multiple IC's on back of PCB.

[CompGeek]

i was getting as much air on them as i could, i dunno.

I had it on the mosfets next to where you do the vmem mod.

[taotao0210]

i was getting as much air on them as i could, i dunno.

I had it on the mosfets next to where you do the vmem mod.

could you give a picture about which heatsink have you removed?

[Primoz78]

Looks like some a few of 7900GT owners have the same issue with the ram as I do... ...I will take the card to my friend to test it and if the problem will persist I will sold the card and no longer play with pencil mode.

Regards,
Primoz

[CompGeek]

could you give a picture about which heatsink have you removed?

no, i dont

[majestik]

Its the heatsink you put on the mosfets to "prevent artifacting problems" as recommended on evga forums, right?

[CompGeek]

Umm, it was recommended right here.

[revenant]

You guys will never believe what the problem was.

I took that ramsink off my mosfets and everything returned to normal. :S

Now I may have a PSU problem though. I started 06 @ 750/900 and when I got back about 2 mins later my PC was off.

You know what - I took the sinks off my memory controller ICs also and things seemed to have improved when playing fear now.. which is the only game my cards don't seem to like... I think, unless you use very high quality thermal conducting adhesive/compound, that it -can- smother the chips to have those sinks on them.. Anyways.. sometimes the best cooling for a chip is an open chip top with a air going over it I reckon.. seems to have helped in this case.

[xit]

OMG OMG OMG!!

Evga are shipping newer PCB's to customers who have returned faulty cards that give artifacts, and guess what the main diff is? They have added a hardware mod that automatically increases the core to 1.45v in 3D mode!! LOL!

Read about it on page 6 at http://www.hardforum.com/showthread....6&page=6&pp=20

So they have done for 3d only what a penmod does all round. Unbelievable.

BTW, from reading various forums, do NOT attempt any Mem voltmods, and don't go over 800 mem speed. The Samsung mem chips are rated to 1.9v default, and are already clocked to 2v on most PCB's.

BTW part 2, apparently almost all the boards are manufactured in China by Flextronics , regardless of who rebadges it. So save your money and just get a Forsa brand ($420 in Australia), then upgrade to a Zalman vf900 ($55) or water, do the 1.45 penmod and be happy with around 675/800 clocks (i get this using a delta of 50). Laughing all the way to the bank, and forget about XFX in particular (bad RA support).

Bottom line? Stock volts (1.2) and stock coolers are not enough to run the 7900 series well, though the memory is already pushed to its volt limit. nvidia

[Marlowe]

I found out yesterday that Trackmania Nations (a very cool, but Nvidia optimized racing game) will give me artifacts where other programs won't.
I had to lower my memspeed all the way down to 780 to make them disappear. (down from the not so spectacular 850 before). You can download the game and try for yourself to see if you have the same result (it's free).

So I'll be running my card at 700/780 now (1,55V) ..I'm not doing the mem mod and I'm not putting on a sink on the hotspots, as that has caused problem for some also.

[xit]

I found out yesterday that Trackmania Nations (a very cool, but Nvidia optimized racing game) will give me artifacts where other programs won't.

Hmmm, I went to download that game but stopped when I saw the big warning about it being infested with Malware.. ..do you have descent anti-spy?

Have a read of the warning at http://www.gamedaily.com/download/in...eid=0078700913

Sorry if thats off-topic, but I thought I would let other prospective readers know....

[t024484]

The first card that I modded was an XFX 7900GT.
I noticed that I had to connect a 47Kohm resistor from pin 3 to +5Volt creating an offset in Vref of -30mVolt.
With this resistor I could run "Comanche 4 demo" with 710Mhz on the core, without resistor not above 630Mhz.
Ati Tools ran 710Mhz in all cases.

The reason to my opinion can only be that in demanding applications, like Comanche 4, because of a large fluctuating current demand of the GPU, there is much fluctuation on the Vcore.
These voltage fluctuations go beyond the OVP, which then shuts down the GPU.
By making an negative offset of 30mV, there is 30mV more room before the OVP trips. At the same time Vgpu is lowered by 30 mVolt.
I did not experiment with other values, but 47Kohm gave me the stability I needed to run Comanche at the same speed as Ati Tool.

Now I have modified a second 7900GT ( 1.55Volt, 2.1Volt, 45Kohm), this time from Gigabyte.
Much to my surprise I had to apply the same 47Kohm resistor as before to get Comanche at the speed that Ati tool achieved.

So if you are having some stability problems, the best tool that I know to test this is Comanche 4 Demo, apply a 47Kom resistor between the points that I have encircled in light blue in the Jpeg.

Voltmod3.jpg

[s e t h]

i'm posting in this thread so all you 7900gt owners get mailed this.

i have discovered the true baby gtx by the name of sparkle calibre 7900gt 512mb.
unlike the gainward/legend 512mb cards the sparkle 512mb has the same great digital vmod we're all used to.
a friend send me a scan of his card and the vreg design is the same as the 256mb variants.
i will be modding the first one tommorrow and will post some results.
initial testing reveals that the memory will do at least 800 and the core will likely respond in a similar manner to what we're getting from the 256mb cards cores.

[revenant]

yep, looks like a nice card.

(whoops, wrong link at first, lol)
http://www.cdrinfo.com/Sections/News...x?NewsId=16803

[smut]

Can you guys let me know exactly what ramsinks you used on the the IC/mosfets on the back of the card? I have some copper thermaltake sinks but they were too big and would have probably shorted the card out. They were also too big to have one on the little IC and the longer rectangular one. I just need a recommendation on what sinks you guys used that were small enough to be able to have two close to each other? I remember someone saying the OCZ alum. ones worked great but havent found the post again. Has anyone used the blue small zalman sinks to sink the hotspots on teh back of the card? Thanks in advance, ordering some new sinks but wanna make sure I get ones that will fit/work before I waste my money again. Thanks

[smut]

Edited because you fixed the link....

[revenant]

Not really, considering you linked to a 6600GT LOL!

it's been corrected for a while. changed the link a couple mins afterwards..

Also, I can't seem to find any mention of the p790 calibre on sparkle's site.. pretty strange.

[xit]

Can you guys let me know exactly what ramsinks you used on the the IC/mosfets on the back of the card? I have some copper thermaltake sinks but they were too big and would have probably shorted the card out. They were also too big to have one on the little IC and the longer rectangular one. I just need a recommendation on what sinks you guys used that were small enough to be able to have two close to each other? I remember someone saying the OCZ alum. ones worked great but havent found the post again. Has anyone used the blue small zalman sinks to sink the hotspots on teh back of the card? Thanks in advance, ordering some new sinks but wanna make sure I get ones that will fit/work before I waste my money again. Thanks

I used one of the copper Thermaltake ones but straddled it across all 3 mosfets. Admitedly a tiny bit of the 2 smaller ones is still exposed, but it does a good job as I can now rest a finger on it without it burning me.

I asked some opinions previous and the answers I got indicated that copper was better than aluminium.

[quijonsith]

I've got some zalman ramsinks coming in tomorrow to use on the back of mine. I'll let ya know how it goes.

[s e t h]

sparkle has a separate site for the calibre range: http://www.calibrestyle.com.tw/main.asp

not very informative but its there

[alpha0ne]

sparkle has a separate site for the calibre range: http://www.calibrestyle.com.tw/main.asp

not very informative but its there

If you click on product catalogue / P790 at least you can get some piccies, I've got some full size pics that I'll post later if anyone wants me to or better just d/load them from the site under d/loads

Bought the card today, should have it by ~ next Monday

[smut]

I've got some zalman ramsinks coming in tomorrow to use on the back of mine. I'll let ya know how it goes.

whats the word? or since you posted after midnight did you mean Wednesday?

[quijonsith]

For some reason UPS didn't budge today. I guess they took an extra day off after the holiday. Friggen *&%*($&%. It's an hour and a half away and has been since friday but they decided to take a four day weekend. If the shipping cost hadn't been so low I'd petition newegg for a refund on shipping. It should be here tomorrow.

[wtkprol]

Where can you get one of these "baby gtxs"? lol