SLI Crashes, Underclocking fix, PSU the reason or not?

VesoRakia

New member
Hello guys,

So I have the following situation: I have recently installed a second GTX 660 in my system and managed to run SLI (almost impossible task on a non SLI mobo with a crappy PSU, but with some rewiring and a software that enables sli on some unSLI mobos (called DifferentSLI - amazing little tool) it works fine even with the newest drivers).

The thing is that the most demanding games often crash (black screen, nvidia driver error). Since i've had crashes like that when i was using just the single Palit GTX660 and OCd it, i tried underclocking both by 10%. This completely fixed the issue.

I was lead by many forums to believe that this might be a PSU issue (mine is a really crappy brand (turbo-x) but says it is 750w, which i dont really believe).

I do not think it's the PSU and my wiring's fault because of the following. The Palit GTX660 was totally unoverclockable even on its own (+2% OC and games crash). The MSI 660 one on the other side, overclocks beautifully on it's own with no crashes at all (on the same PSU). So my question is doesn't that surely mean that i just got a shitty palit 660, or it still might be from the PSU, despite the fact that the MSI one can OC a lot with no problem ? If it's the PSUs fault, how come the MSI does not crash, and the Palit crashes when OC'd on their own?

I want to know this as I wonder, would I be able to OC the stupid Palit GTX if I got a better PSU?
 
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If you have a really shitty brand then youre really not going to be able to tell till you change it.

Your shitty psu is probably slowly killing your rig anyways.....

As for the "stupid palit" I hate to say it fella but grow up.
 
The Palit card is probably a little faulty but your poor quality PSU and rewiring probably isn't helping things...

Is it the basic Palit card with the blower cooler?
 
Well by "the stupid palit" i meant MY faulty Palit, not that all palits are stupid. I guess i just drew the short straw from the silicone valley lottery ...

And yes it's the Palit GTX660 with one blower looking kinda like a stealth jet or a lamborghini (edgy). The MSI GTX 660 is the twinf frozr OC one (2 fans and is a bit bigger)

As for the PSU i just can't see how is it possible for an MSI GTX 660 to overclock wonderfully (up to 10% - 15% on all clocks and power) with no problems at all, and the Palit to crash on everything more than +15 Mhz GPU Clock. (that's tested using just one GPU with the stock wiring). Is it possible for the MSI one (more OCd and with +1 fan) to draw less power or something?

I fixed the game crashes by underclocking the SLI system by not more than 2-5% (The 5% underclock of the Power % seems to do the trick, although there are rare crashes if i don't underclock the clocks by just a fraction (e.g.-15Mhz).

P.S. I dont think the temperature is an issue, the system doesn't heat up too excessively when I push the fans to work overtime ( max 74C on the twinfrozr, 79C on the palit)
 
P.s.s.

I've decided to listen to you and finally get a new PSU. As I know my rig is getting older and older, and soon it's gonna be time for a full change. Would you please recommend a PSU that will be good now and for the next one.

Right now I am looking at Corsair CX750 for nice prices? Do you recommend this as a good PSU that will be able to accomodate some new components for the next 5 yrs lets say?
 
We can't say yes or no as we don't know the exact specs of your current system, and what you intend to upgrade to over time....

Without this knowledge, we can't say yes or no, only a yes for the current system.

As for what to get, anything Seasonic, Corsair, EVGA, Superflower or Coolermaster
 
The fact you have modified via rewiring, and using 3rd party software aka DifferentSLI, you can't really get the full support you want as you as somewhat "hacking" a system to force it to do something that it wasn't intended to do.

The PSU change will certainly help you, but I think you will continue to run into issue without changing to hardware that supports SLI e.g. Motherboard.

As "youwhat" states. We need to know your full specs in order to help, other wise we are just shooting guesstimates at you.

CX750 is not a bad psu at all. More than capable of handling your SLI 660s. One thing you havent mentioned that everyone here will suggest you not to do, and that is use those nasty little Molex/PCIex extensions that often come free with cards. Its much better to use the cable that comes with your PSU that plugs directly into the gpu cards.
 
Thanks @Warchild for the detailed comment. Yes I am currently using a mix of cheap chinese cables since my crappy PSU has just a single PCI-E 6pin plug.

From all I've read the Corsair CX750 is an excellent PSU.

The thing is that i just found an EVGA SuperNOVA 1000 G2 Power Supply for the same price (2nd hand) with a lot of warranty left. It's definetely an overkill, but at that price why not?

The 3rd choice is Super Flower Golden Green HX 650W. Im not familiar at all with the brand but i hear positive opinions. It's gold certificate and has 4x 6+2pin which is good to have for future SLI possibilities.

Since I've found the 3 at relatively same prices (the EVGA is 2nd hand tho) around 100$ which one would you get?
 
Thanks @Warchild for the detailed comment. Yes I am currently using a mix of cheap chinese cables since my crappy PSU has just a single PCI-E 6pin plug.

From all I've read the Corsair CX750 is an excellent PSU.

The thing is that i just found an EVGA SuperNOVA 1000 G2 Power Supply for the same price (2nd hand) with a lot of warranty left. It's definetely an overkill, but at that price why not?

The 3rd choice is Super Flower Golden Green HX 650W. Im not familiar at all with the brand but i hear positive opinions. It's gold certificate and has 4x 6+2pin which is good to have for future SLI possibilities.

Since I've found the 3 at relatively same prices (the EVGA is 2nd hand tho) around 100$ which one would you get?

Personally out of all of the above listed (without knowing your hardware specs), I would opt for the Superflower unit, as I can imagine quite a few people on here, as with second hand goods, unless you know the person, you don't know what your getting, and whether it has developed a fault or something which that person has cause or something else to invalidate the warranty on the unit, also if it needs to be replaced the retailer or manufacturer will return it to the address on the invoice, not your address as that is the proof of ownership and warranty.
 
EVGA's PSUs are rebadged superflower units and they're often cheaper than Superflower's own brand. I'd go for the superflower personally. If you want to save money but still get an amazing PSU look at evga's supernova series.
 
I got the EVGA SuperNOVA 1000 G2, really cheap for 100$, used one month with almost 10 yr warranty left. I guess I'd use this monster a long time, but it didn't help with the OC problem. Stupid Palit keeps crashing, so I guess it's just crappy. The wiring looks a lot better now tho.
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How about trying without any overclock?

It could actually be an nvidia driver or 3rd party software fault to be honest.
 
I am actually having to underclock just a fraction in order not to have crashes. Anything at 100% or more results in occasional crashes (sometimes 5min sometimes 1h). I don't think it's software issue, since I've been having this with this GPU throughout many windows reinstalls and for more than a year.
 
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