Upgrade 780ti to SLI 970

Hi folks,

As the title I'm looking to part ways with my 780ti which as served me extremely well for the last 12 months. I just have a couple of 'newbie' questions on the SLI setup.

My initial concern is heat. My MSI 780ti is reaching 68c currently, which is perfectly fine IMO. I would like to go with MSI again but would I be better going with standard GTX's? I have a Corsair Carbide MID tower case and room inside is quite limited. Do the non reference cards disperse heat better in a SLI setup than non-reference? Any advice on this would be great!

My second concern is power. I have a Corsair RM850. Simple question really, will this be okay? I've seen Hilbert's review so I assume so, but I wouldn't mind some advice from someone who's got a similar setup.

Thanks :nerd:

 

I don't know how well two 970's will work in that case, also not sure exactly which corsair carbide you have.

My case has 3 intake fans at the front, two of which push air pretty much directly over my SLI'd Gigabyte g1 970's.

They can hit over 70 degrees at full usage, which isn't really all that hot.

I run this on on Antec 750watt PSU with four 25 amp 12v rails.

No issues whatsoever, so I assume your PSU would be fine, with the single 12v rail at 70ish amps.

Again, no idea how well your case would handle the heat from two cards.

Should probably wait a bit and see what you can get ina single card solution with the upcoming releases from both companies.

 

750/12=62.5 amps on the 12v rail. You cannot multiply 25 amps x4 rails.

 

You should be ok as far as power goes. But what Corsair carbide case do you have there are alot of them.

 

Each 12v rail is rated to 25 amps. There is a limiter on each, and of course the single 12v source that is split among the 12v rails cannot exceed the combined ~750w (62 amp) limit (at least with any kind of clean or reliable delivery.)

No one (including me) was implying that.

Thanks for stating the obvious, though.

The point was that even with a split, limited 12v system, everything runs fine, so his higher powered single rail system should not have any issues.

I guess I'm stating the obvious too, now.

 

I get the impression you just looked that up.

 

You'd be mistaken.

 

GTX970 is a "sipper" compared to a GTX780Ti. There really shouldn't be any issue with a quality 750watt unit powering 2 cards in SLI. That said, a Corsair RM850 should easily power a pair in SLI with room to spare. It's specs seem to imply that it's an 850watt continuous power unit.....

Assuming the unit produces 62A on the 12V rail which is unlikely for an Antec 750watt unit.

The amperage output will vary depending on how much power is actually available on the 12V rail. The Antec EarthWatts EA750 can only handle 56A maximum across the 4, 12V rails, all of which are rated for 25A individually. With a 56A limit, this means it only has 672W available on the 12V rails.

 

I suppose you assume I have the Antec EarthWatts.

If I remember correctly, my PSU was indeed rated at 62 amps, and tested at that.
I remember seeing testing very close to 750 watts on the 12v with good results, which is why I picked it.

tp-750 blue.

I'm not really sure how me saying this persons better (on paper) than my PSU should have no issues running a similar setup turned into some weird ass bull**** from you two, but I guess either take it to PMs or start a new thread or something and let this guy tell us what case he's using.

 

Actually, I didn't assume anything. I simply Googled "Antec 750watt PSU" and the EA750 was the first model listed and appeared to be a good example based on the rated per-rail amperage.

The case really makes little difference. If the OP wants to go SLI, he's best served by a pair of cards using blower style coolers. Of course, if we're so concerned with the case he's using, a quick review of his specs says he's using a Corsair Carbide Series SPEC-01. Unless of course he's changed cases and not updated his specs. If he's still using that case, he'd be best off with 2 cards using blower style coolers as installing 2 fans in the front of that particular case doesn't really improve air flow due to a harddrive cage completely blocking the lower fan.

 

When somebody states they have 4 25amp rails on a 750 watt psu and says a more powerful 850 watt should be fine makes me wonder. If your 750 watt psu is enough for sli than a single rail 850 watt psu will have room to spare.

 

Thanks for the replies gents. I have made the plunge and ordered two they should be here tomorrow so I'll report back

 

Enjoy.

 

Note I stated amperage for his single rail 850. My point was to that despite any given rail of my own 750 PSU limited to 25 amps and running a similar setup fine, that his, assuming similar quality, would be fine as well.

In any case, have fun with your SLI'd 970's, OP.

I dunno why (well, I kinda know why), but I stopped playing games really about a month after I got my second 970.

I'm sure I'd be having fun with it if I were playing games, but I think I'm going to move one to my leftover-build-HTPC. I'd leave it if the only 3d programs I currently use weren't non-SLI apps.

 

Got the cards set up yesterday! All was fine, temps are great IMO 64c on the top card & 42c on the bottom card. Spent the day on GTA will go back to other games soon to see the improvements
Power supply seems fine too (no crashes etc) but guess time will tell on that. I'm assuming the PSU life's expectancy will go down as a result of the increased power needs?

Only issue I've come across is I noticed DSR was not shown in the NVidia CP. After a quick google search it seems that DSR is unavailable currently with SLI configs. I was hoping to run elite dangerous @ 4k but guess I'll have to wait for the guys at NVidia to sort out... Anyone know when this is due a fix?

 

Grats.

bottom is 42 under load?

 

Yeah, according to GPUZ. Played several hours of GTA and 42c was max temp for the bottom card.

How can I tell the utilization of each card? Would be interesting to know how much the second is being stressed etc

 

afterburner will show you card utilization, can set up an overlay to view while in game.

 

Thanks, I'll give this a go.

 

Just noticed that dsr is missing and unless I am going completely crazy I have definitely used it with sli enabled. Maybe a driver bug
Also if you run the card with the highest asic in the top slot the cards run within 1-2 degrees of each other instead of 10+ the other way around. I know it sounds crazy but i went back and forth a few times and it was always the same