PDA

View Full Version : 7900 GT runs 30 cooler with new heatsink, and memory fails???


rev_b
10-21-06, 12:31 AM
Hi there.

After some years sticking with ATI (last nvidia card was a Ti4400) I got this cheap Manli 7900 GT that indeed was a great upgrade for my Radeon X800pro. All was well, except for insanly high GPU temps. Normal until 85c, Nvidia says - well, it actually hit it while gaming. Another annoying thing was the irritating high-pitched noise the tiny fan did, and guess what - fan speed control doesn't work. Ok, known 7900 GT "feature".

So, next step was to buy a Zalman VF-700 AlCu cooler. Installation was quick, and I was pleased to see that temperatures were in the high 50's, in load. Great, I thought. Let's overclock. Letting the drivers to find the "best speed" gave me an imediate crash with screen corruption... not good. It previously gave something like 495/750, but I actually never overclocked it (tested it a few times at that speed, but it almost hit 90), because I was waiting for better cooling.

So after a few hours of troubleshooting, here's what I found:

- Card artifacts at default speeds in Deep Freeze 3dM06 test and crashes in Half-Life with screen corruption

- I had to UNDERCLOCK the memory speed to 637 Mhz, that stops the artifacting

- Core speed and temps are not a problem, core can be overclocked to 550 Mhz, max temp 60c under load, but pointless, as the memory is holding it back

- Removed RAM heatsinks and reinstalled the Zalman cooler, same results

- Ran with the stock fan connected to the card fan header, not a difference.

I'm happy with one thing, no more noise. These Zalman coolers are really nice - and they show how poor the stock cooling is. The performance isn't bad even with the underclocked memory, but I'm worried. Did I damaged the card?

SLippe
10-21-06, 12:42 AM
First of all...

I, too, love the Zalman coolers and I highly recommend them.

Second...

All the issues you are stating are known 7900 issues, but were later fixed by most manufacturers. I'd suggest an RMA or maybe a different brand, like eVGA. You might check with your manufacturer and see if they have a BIOS update, but I don't know if that would fix the problems or not. I am thinking it's more hardware related than BIOS, but maybe not. Someone else will have to elaborate on that. The 7900 GT is a great card! Good luck.

K007
10-21-06, 12:48 AM
Sounds like a dud 7900GT. RMA ftw..check ure ram type...new one is called infenion.

rev_b
10-21-06, 12:48 AM
First of all...

I, too, love the Zalman coolers and I highly recommend them.

Second...

All the issues you are stating are known 7900 issues, but were later fixed by most manufacturers. I'd suggest an RMA or maybe a different brand, like eVGA. You might check with your manufacturer and see if they have a BIOS update, but I don't know if that would fix the problems or not. I am thinking it's more hardware related than BIOS, but maybe not. Someone else will have to elaborate on that. The 7900 GT is a great card! Good luck.

But the card was working fine before I assembled the new heatsink... :(

rev_b
10-21-06, 12:49 AM
Sounds like a dud 7900GT. RMA ftw..check ure ram type...new one is called infenion.

This is samsung 1.4ns

SLippe
10-21-06, 12:54 AM
You did put Thermal Paste on the GPU, right? I know, I know. What kind of TP did you use? If you used Artic Silver, you can short components out if it spreads too far. I don't know. If all that is cool, then it does sound like a bad card.

rev_b
10-21-06, 12:59 AM
You did put Thermal Paste on the GPU, right? I know, I know. What kind of TP did you use? If you used Artic Silver, you can short components out if it spreads too far. I don't know. If all that is cool, then it does sound like a bad card.

Yes, I put the thermal paste that zalman provides with the Cooler.
I don't think I can RMA it, as I don't have the receipt of purchase, it was a cheap deal, and I can't really complain as the card was working 100% until I put the new heatsink...

AdmiralHalsey..
10-21-06, 05:08 AM
7900's break when you overclock the memory, sometimes even slightly. Trust me on this...

ATOJAR
10-21-06, 10:07 AM
Yip... as said the 7900 range are well known for faults, especially the memory failure, take it from someone who had had two 790 GTX's fail in the past, RMA it, you will eventually get one that works, the 7900's are a bitch for faults BUT when you get one that works..... there a daddy of a card!

rflair
10-21-06, 10:22 AM
Since you can't RMA the card as you said there is one more thing you can try, get some Isopropanol 99% (rubbing alcohol) and a tooth brush (new), dip the tooth brush in the alcohol and scrub the card clean (every part of the pcb), let it dry for about 1 minute and retry the card.

This is just to make sure that any residue, thermal paste, finger oils and dead skin are removed.

Your card does have the troublesome Samsung memory that had a higher then normal failure rate.

rev_b
10-21-06, 11:58 AM
Just great. And I thought I was getting a great deal for the same price of a X1900 GT...
What kind of a card dies just for overclocking memory a bit???

rev_b
10-21-06, 12:20 PM
Just one more thing: does it tend to get worse, or what? I can live with the card at 530/637, it was cheap, it still performs great, and, best of all, the card is now silent.

K007
10-21-06, 12:51 PM
I had to underclock my gts from 800 to 500 to get stable..out of the box..lol and this is 2 GTX cards..had no where to go but the 7950gx2

rev_b
10-21-06, 12:56 PM
But what does actually happens to the card? RAM gets damaged, or what? I never have seen RAM to fail unless it's overvolted; if it can't take that speed, it just starts to give errors and nothing more...

Man, if I would knew this, I would never have got this card. Maybe this is because they're selling so cheap now...

Roadhog
10-21-06, 01:48 PM
Underclock it for like a couple weeks, then see if it will overclock to like 500/1.4 again. Same thing happened to mine, it artifacted like hell after a week of having it, then I underclocked it and it was fine. So after a week or so I tried overclocking it again and it worked perfectly.

rev_b
10-22-06, 07:46 PM
What a crazy card.

After reading (and freaking out) with the zilion threads about this 7900 GT fiasco, I did attach 2 heatsinks (from the zalman kit) to the "known" hot spots in the back of the card. I also updated the motherboard bios (Asrock Dual-Sata2) and today I tryed again, based on Roadhog post... and it works now with memory at stock speeds... I do feel it' ll break any moment now, but truth is the card is now running at 540/660 and I looped 3DMark06 Deep freeze five times and it didn't artifact. I also ran HL2 Lost coast (actually the card only artifacted at default speeds in these two apps) and I didn't spot any artifacts either.

I'll leave it as it is and see what happens.

I also found that 7900 cards can't do HDR and antialiasing at the same time. Old news, you may say, but strange thing is that reviews never actually mentioned it... Why do I have the feeling there's always a catch with Nvidia hardware?

crainger
10-22-06, 08:04 PM
What a crazy card.

After reading (and freaking out) with the zilion threads about this 7900 GT fiasco, I did attach 2 heatsinks (from the zalman kit) to the "known" hot spots in the back of the card. I also updated the motherboard bios (Asrock Dual-Sata2) and today I tryed again, based on Roadhog post... and it works now with memory at stock speeds... I do feel it' ll break any moment now, but truth is the card is now running at 540/660 and I looped 3DMark06 Deep freeze five times and it didn't artifact. I also ran HL2 Lost coast (actually the card only artifacted at default speeds in these two apps) and I didn't spot any artifacts either.

I'll leave it as it is and see what happens.

I also found that 7900 cards can't do HDR and antialiasing at the same time. Old news, you may say, but strange thing is that reviews never actually mentioned it... Why do I have the feeling there's always a catch with Nvidia hardware?

They can do HDR+AA in some cases. Have a look at CoH, HL2:Ep1 and Dark Messiah.

rev_b
10-22-06, 08:33 PM
They can do HDR+AA in some cases. Have a look at CoH, HL2:Ep1 and Dark Messiah.

Yes but not with HDR FP16, apparently.

Anyway, if it keeps working, I'm more than happy with the card. It was cheap, doubled my Radeon X800 speed at half its cost two years ago, 2d quality is top notch (I missed digital vibrance :)) , it's quiet now, and nView is way better than ATI's jurassic Hydravision, using multimonitor is more responsive, tweakable and intuitive than with ATI software.

This artifacting issue is very annoying actually. As far as I can see, updating motherboard bios may have somehow improved it - at least the card can run at default memory speeds now. Very strange.

Dazz
10-23-06, 10:35 AM
What mobo are you using some boards like ASUS PEG and MSI overclock video cards automatcily.

rev_b
10-23-06, 01:57 PM
What mobo are you using some boards like ASUS PEG and MSI overclock video cards automatcily.

Asrock Dual-Sata2 (ULI M1695). Definitly the bios update *seems* to have helped a lot. Anyway, it's running CPU/PCIe assync, HTT 250Mhz*4, Venice 3200+@2500Mhz with PCIe @ 100Mhz.