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750W for SLI GTX 770 and FX-8350?

HCkev
  • 81 months ago

Hello,

I'm currently planning a build for a friend. I will build it for him later this year (probably in november). Here is the part list so far: http://ca.pcpartpicker.com/user/HCkev/saved/1cvW

Of course, the choice of parts might change until I'll build the PC, depending on the deals available in a few months (and if AMD release the Radeon 9000 series, I might consider one of these).

Right now, I plan on a GTX 760, but my friend told me he might be able to spend a bit more money that what he originally planned. So, the logical upgrade for better gaming performance is getting a better video card(upgrading the CPU wouldn't give that much benefit), and the GTX 770 sounds like a good candidate. Of course, there is a single GPU in the build right now, but he plan on adding a second card in SLI 2-3 years later as an upgrade, so the build will need some PSU headroom to support the additional card.

While the Thermaltake Smart 750W (Which is the same internally as the Corsair TX750, according to TechPowerUp) is definitely enough for SLI GTX 760, I fear it might be a bit short on power for SLI GTX 770.

I will overclock the CPU, as much as the H60 will allows (maybe something around 4.5GHz?), and since the FX-8350 does consume a bit more power than the Intel equivalent, I think it's something to take into consideration.

Nvidia recommends a 850W for SLI GTX 770, but those recommended wattages are often a bit exaggerated... They also recommend 62A on the +12V rail, which is what the PSU rated for - So I assume it will be fine. Right?

PcPartPicker's power consumption with dual GTX 770 is estimated at 705W. With the overclocked CPU, it will probably go over 800W... Now, I assume this PSU will probably be able to handle a 800W load without problem like most good PSUs, which are often able to deliver more than what they are rated for. I also guess that this is the maximum wattage the whole build would consume in the worst scenario (i.e., stress testing to run the system at 100%), so the real world usage for gaming would probably be less than that. But I'm not sure if I should take the risk or go with a 850W instead, which will make the build price a bit over the budget...

I did a bit of googleling, and some people says it's enough, others says it's not... So I'm confused. Any advice? Is anyone successfully running dual GTX 770 using comparable or lesser 750W PSU?

Thanks in advance!

Comments

  • 80 months ago
  • 2 points

One of my Rigs currently run Gtx 770's in SLI with 760w, You should be fine.

-Tyler

  • 80 months ago
  • 1 point

Thanks, that's encouraging. I don't think a 750W would blow up because it has 10W less, ahah! :P

  • 80 months ago
  • 1 point

I don't think you can estimate what the power requirement will be for SLI two or three years from now. It may go up, it may go down. I would buy a PC for the current card and expect to change the PSU when you add the second card.

If BoltAction says that the Thermaltake 750w will work now, then I would save money and buy that instead of 850w.

  • 80 months ago
  • 1 point

Any easy way to check is simply add both cards to your buildlist and get the estimated wattage your system is going to require. When you add another card to it the wattage estimate is 585w. 750w in this case would be plenty.. however if he is going to be trying extreme overclocking and adding more HDD/SSD to it in the future it could be safer to go with 850w so he doesn't have to upgrade the PSU down the road.

Edit: those wattages were with that 760 card sorry. The estimated wattage with two of these Gigabtye 770 is 705. So in a safe choice I'd go with the 850w PSU for future upgrades

  • 80 months ago
  • 1 point

Thanks for your input. He is not really an enthusiast (he never build a PC, so i will build it for him and overclock it too), and I don't plan on making extreme overclocking (It would need a better CPU cooler to do so). Probably no more than 4.5GHz(500MHz increase), although I have no experience with the 8350 yet, so it's hard to guess how much OC I will be able to pull off with a Corsair H60 - But I don't expect too much.

Yeah, 850W would be the safe bet... But I feel like the 750W might be fine under real-world usage. The only upgrade he plan on doing is adding a video card, and maybe adding more RAM(which shouldn't add that much more wattage), but 8GB should be plenty for the next years, unless games suddenly start using more RAM.

Still a hard decision :P

  • 80 months ago
  • 1 point

The main thing to look at is the amperage @ 12V, in this case you need 62A @ 12V, as you've stated. If your PSU can supply this, you should be fine.

  • 80 months ago
  • 1 point

Yep, the PSU is rated for 62A, which meets Nvidia's recommendations. But of course, it's a good habit to take something slightly better than what's recommended.

But I feel that PSU requirements are often over-estimated. With my current PC, which I built 4.5 years go, I made the mistake of choosing a Cooler Master eXtreme Power Plus 600 PSU, which I later figured out it was a crappy PSU and that it isn't safe to pull more than 450W from it(according to Hardware Secrets). I'm probably pulling around 500W from it with my current specs and it still works fine... Might be luck. But this time, the Thermaltake Smart 750W I plan using actually received good ratings, so there should be no risks. Harware Secrets were able to safely pull 900W from the Corsair TX750 v2, which is the same as the Thermaltake internally. Should be fine I guess...

  • 80 months ago
  • 1 point

850w, the rule of thumb is to give yourself reasonable headroom. If your running near full load of your PSU that's not good

  • 80 months ago
  • 1 point

Well, obviously I don't want the PSU to run at its rated power all the time, but how many time the CPU and GPU will be both running at 100%? Very rarely, it might be pushing the PSU a bit when stress-testing the CPU and GPUs altogether, but it will otherwise probably be totally fine under real-world usage, I think.

Just like overclocking, many people keep the CPU at 80°C when running Prime95; Obviously, you don't want your CPU to run that hot all the time, but it only get so hot when stress-testing for several hours; It usually runs a fair bit cooler under real world usage.

I feel that 750W will be "just okay" - It will work without problem, but simply not the "best case scenario". It probably won't be safe to do much more upgrades than adding another 770 - But I highly doubt he will do more upgrade than that.

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