• Welcome to Overclockers Forums! Join us to reply in threads, receive reduced ads, and to customize your site experience!

** 2x7800GTX (v-modded & TEC-cooled) ** (w/ pics)

Overclockers is supported by our readers. When you click a link to make a purchase, we may earn a commission. Learn More.
Thanks for the replies guys. . . .

@ bryan_d - Come to think of it, I think you probably guessed it right with mentioning the voltage regulator chips getting crushed. That would explain why neither the GPU or memory are getting power even though there's 12V at the PCI-E power connector. . . . I think that's the first thing I'm going to check out. . . . If they're crushed, is there an easy way to replace them or is the card dead?

@ veryhumid- That's a good idea to let one dangle while testing the other but I think I'm going to have to pull the top card completely out anyways to try to see what's wrong with it. So there's no way of getting around draining the system and taking the waterloop apart again. :rolleyes:
 
Mate,

You absolutely must reinstall the drivers for it to detect SLI. This is a bug in the drivers we are seeing. I have had two SLI setups and both did the exact same thing you describe. I would recommend the following procedure:

  • Use one card and uninstall the drivers
  • Put the second card in and restart. Windows will come up.
  • Use drivercleaner to remove ALL traces of the recently uninstalled drivers
  • Now, reinstall the drivers.

I think you can handle it from here :)
 
Thanks for the info, SuperNade. . .

However, I think there is a more serious problem than simply enabling SLI. I mentioned earlier that the GPU and memory aren't getting any voltage. That shouldn't be the case, even if SLI is disabled. . . . I suspect (as it was suggested earlier) that the voltage regulator was damaged. I'm going to have to take the card back out, pull off the voltage regulator fan and heatsink, and inspect the chips. . . . Hopefully I can repair/replace them and not lose the card.
 
Revivalist said:
Thanks for the info, SuperNade. . .

However, I think there is a more serious problem than simply enabling SLI. I mentioned earlier that the GPU and memory aren't getting any voltage. That shouldn't be the case, even if SLI is disabled. . . . I suspect (as it was suggested earlier) that the voltage regulator was damaged. I'm going to have to take the card back out, pull off the voltage regulator fan and heatsink, and inspect the chips. . . . Hopefully I can repair/replace them and not lose the card.
Click to expand...

Hay CR, sorry to hear about this speed bump. I'd have replied much sooner, but YOU KEEP CREATING NEW THREADS FOR THIS PROJECT, INSTEAD OF PUTTING IT ALL IN YOUR ORIGINAL THREAD :mad: (the one which I'm subscribed to). Keep it all in one thread, PLEASE!

I was looking closely at those very high res photos, and I noticed something strange. There is some kind of white FOD (foreign object debris) covering two gold trace pins of the PCIe connector on the bottom 7800 card in the first photo of your post. Is that intentional? Part of the volt mod? I can't compare those same pins to the top card in the photo as they are glared by bright light (I'm not educated on v-modding) If not, get that FOD removed, as it may be causing a short within the card, or a "no connect" to the corresponding PCIe slot pins. If it's not intentional, I hope it's not a drip of thermal adhesive, which may prove difficult to remove without damage to the underlying gold traces. Also, make sure the FOD didn't contaminate the contact pins in the PCI slot on the motherboard. If it did, get it out somehow.

Additionally, you've probably already adressed these things, but just in case you haven't:

1. Connect a 4 pin floppy disk style cable from your PSU to location J1 on the DFI motherboard. It is "recommended" for SLI "system stability" in the manual. Manual says it's not required for the *motherboard* to function, but interestingly omits whether or not it's required for the SLI setup to function. J1 is in between the DIMM bank and the first PCIe X16 slot, toward the top back edge of the PCIe X16 slot.

2. Your PSU should have a secondary motherboard +12v power connector for the CPU's VRM. It will be either an 8 pin or 4 pin connector. Make sure this is connected to location C1 on the motherboard, next to the main 24 pin connector. If your PSU has the 4 pin style, look in your motherboard manual for connection orientation.

3. Connect the video cards' 6 pin auxiliary power plugs to *separate* 12v PSU rails. It would be a good idea to connect one 7800 and 3 hard drives to one 12v rail, and the remaining 7800 and the rest of the hard drives to the other 12v rail.

Oh, one last point. If you get that card to work as a standalone, and you've covered *everything else*, it's always possible that the motherboard is defective, assuming you've not attempted SLI with this motherboard previously. I don't recall if you stated you have. Did you test that 2nd 7800 "out of the box", before modding it?
 
Last edited:
Hi Hardware Freak,

I'm sorry about the separate threads. I sort of considered this to be a separate project because I abandoned the 7800GT and went to work on these two 7800GTXs. I posted my last thread in the extreme cooling section because I was focusing on the pelt setup, and the BIX III with three Panaflos. . . . This time I was focusing on the video card performance.

Anyhow, thanks for the suggestions. . . . I didn’t notice that debris before. Thanks for point that out. I’ll be sure to clean it. . . .

I do actually have all the power cables connected. That includes the 24-pin motherboard power, 8-pin CPU power, floppy power connector (for SLI), and the 6-pin PCI-E power to each video card. . . . The DFI Expert board doesn't have the extra 4-pin molex connector that the older SLI-DR does. It only needs the extra floppy power connector. . . .

The OCZ 520W SLI PSU that I’m using has two 6-pin PCI-E power cables. It also has separate cables for the HDDs as well. So none of them are sharing the same cables. . . .

I’m pretty sure that the problem is not the motherboard but the video card. Viper John mentioned to me that the motherboard slot has nothing to do with the video card’s onboard power supplies. So the fact that the GPU and memory aren’t getting any power means that something is wrong on the card. I haven’t had a chance to take things apart and inspect them yet. But I think I'm probably going to have to send the faulty card to John and see if he can fix it. I’ll post back when I have some results. . .

Thanks again for all of your suggestions. :)
 
Last edited:
Have you tried undoing the voltmod on the card that doesn't work?
 
Revivalist said:
I'm probably going to have to send the fault card to John and see if he can fix it. I’ll post back when I have some results. . .
Click to expand...

Before you send it to Viper John, clean that FOD off the PCIe card edge, and any that may have been deposited into the seconday PCIe slot. Then test that card individually in the primary slot. Do hook up the 6pin, but dont hook up the water loop to the card (to save time). Make sure the pelt isn't powered. Just power on the system and see if the system will POST and that you get BIOS/text video output. If you do get POST video output, then you know the card is working, at least to an extent. Power down immediately so you don't heat damage the GPU. If you get beep codes and no video output then you know the card isn't working at all. Power down immediately to prevent heat damage.

Now, if you *DID* get POST video output, reconnect the water loop, but only with this single *questionable* card in the primary slot. Boot the system as normal for a single card config. Go into the BIOS and disable SLI. Allow the system to boot into windows. Launch the video driver nVidia control panel, and check all the settings out. If everything looks good, fire up a 3D app. If at this point 3D works, you know this card is now good obviously. Power down, insert the other card into the secondary slot, do all the hardware/water connection juggling, etc/etc/etc, power back up, test SLI again.

Not to denigrate Viper John's knowledge or ability, but the nVidia cards draw power from two paths, both the PCIe slot power plane, and the external PSU 6pin connections, *NOT* solely the 6pin PSU path.

Revivalist said:
Thanks again for all of your suggestions. :)
Click to expand...

You're welcome. I hope that you're able to get it going, and that the 2nd GTX isn't perma damaged.
 
very nice job Revilalist, I hope you get it fixed. Viperjohn is a cool guy, he'll fix em for ya!
 
Hey guys. . . .

Thanks for resurrecting this thread. (Very appropriate for Easter, by the way! :) ). . .

I haven't gotten around to pulling out the bad card and sending it to Viper John to have a look at it. (Things have been too busy with school, work, family, ministry, etc.)

But I plan to do it in the next few weeks. In the meantime I've been tweaking the working card and trying to see what I can get out of it. So far the max in 3DMark05 has been 10,510 but I have a feeling there might be a little more in her. . . .We'll see. . . .

Then hopefully I can get both cards running that well together. :D

By the way, Adam, have you gotten that rig together with the Viper John modded card? . . . I'm lookin' forward to seeing what that thing can do.
 
Revivalist said:
Hey guys. . . .

Thanks for resurrecting this thread. (Very appropriate for Easter, by the way! :) ). . .

I haven't gotten around to pulling out the bad card and sending it to Viper John to have a look at it. (Things have been too busy with school, work, family, ministry, etc.)

But I plan to do it in the next few weeks. In the meantime I've been tweaking the working card and trying to see what I can get out of it. So far the max in 3DMark05 has been 10,510 but I have a feeling there might be a little more in her. . . .We'll see. . . .

Then hopefully I can get both cards running that well together. :D

By the way, Adam, have you gotten that rig together with the Viper John modded card? . . . I'm lookin' forward to seeing what that thing can do.
Click to expand...

Not yet sir, when I do you'll know :)
 
Revive whats the deal have you got that bad johny up and rockin yet or what?
I have been folowing a good number of your threads because of your use of tec.
Hope you get it all 5 x 5. as I am sure will
 
Hi guys, sorry for the major lag. . . . I've been totally out of the loop for a while now . . . Lots of stuff goin' on (dad-in-law had a heart attack, just had our first baby, just graduated with a masters in physics and looking for a job, and just bought a new truck and doing some mods to it) . . .

In the meantime, it seems like technology is shooting right past me with the 7900s, then the 7950s, and soon G80. . . . It's so hard to keep up. . . . Even when this rig is up and running at full performance, it'll be outdated. . . . Oh well. . . .

But I definitely plan on getting back to completing this project as soon as some time opens up. . . . Hopefully it'll only be a few weeks. . . . I'll certainly post as soon as things are up and running. . ..
 
You must log in or register to reply here.

Similar threads

M
DTT3500 - Liquid Damage - Help Fixing
Replies
2
Views
2K
don256us
don256us
Al_bundy
Alucryl - 3DFX - CNC - Retro pc
Replies
2
Views
376
EarthDog
EarthDog
ratbuddy
Converting my EVGA RTX 3090 XC3 Ultra to a hybrid, and a few other tweaks
2
Replies
26
Views
5K
ratbuddy
ratbuddy
T
Help with white liquid cooled build
Replies
15
Views
924
taotree
T
trafiq
Is 1.45 V too much for an air-cooled i7 7700k running at 5.2 GHz?
Replies
10
Views
3K
trafiq
trafiq
Back