LEPA 650 W Bronze PSU enough for SLI

[David Taquet]

Hi,

Here is my PC (which I built in November of 2014 thanks to the advice of Tom's forum members)

CPU: Core i5 4690
RAM: 2x4GB DDR3 1600
Motherboard: GA-H97-D3H
Drive: 1 optical drive
Storage: 1 HHD +1 SSD
USB devices: 3
GPU: MSI GTX 970 Gaming 4G
PSU: LEPA B650-MB 650W Bronze Certified

As my GPU is slowly started to show its limitations at 1080p (meaning if I want 60 fps, I need high settings instead of Ultra), I am thinking of getting another 970 to use in SLI.

I checked my MoBo, which is SLI capable and I have enough space in my case but I see conflicting posts about PSU requirements for SLI on the internet. I am doing some light overclocking now, but would not need to in SLI.

I checked various PSU calculator sites

http://www.coolermaster.com/power-supply-calculator/

http://www.powersupplycalculator.net/

They both tell me I need 550W to run my PC with 2 GTX 970 in SLI (although that probably applies to Vanilla Nvidia cards)

I realize my PSU is OK at best. And I am not sure (= I don't understand) if it has enough power on each rail. Here are the detailed specs:

https://www.newegg.com/Product/Product.aspx?

What do you think? What would happen if I did SLI and came out short of power? Would it damage my components? Since a used MSI 970 card would cost me 150-200$, I am hoping to keep my PSU as is.

I live in Japan so some of the most recommended PSUs are either hard to find or overpriced.

https://www.amazon.co.jp/s/ref=sr_nr_n_1?fst=as%3Aoff&rh=n%3A2151947051%2Ck%3APSU&keywords=PSU&ie=UTF8&qid=1494465024&rnid=2321267051

Amazon Japan (in English) is my best shot if I need to change it. As for the currency,

10,000 yen is 87 dollars.

Thank you so much,

David

 

[Karadjgne]

Sli gtx970 you are looking at @700w with at least 42A minimum recommendation. That's for a decent psu. While that Lepa technically meets amperage needs (barely) and some would quibble about the necessity for 700 since the cards only pull @150w, what you'll find is that your psu is only good for @2/3rds of its rated power. Pushed close to max, it'll almost certainly fry.

Your best alternative is to try and get $200 for your current gpu, and putting the proceeds plus what you were looking to spend on the extra gpu, towards a better single card that won't tax the psu as hard. Otherwise you for certain if staying with the sli will need to also replace the psu.

Gtx1070 comes in right around the $400 price, ¥50k or so.

 

[David Taquet]

Thanks. So if I get it right, the problem is not that my system will draw more than 650W, but that my PSU is incapable of delivering it?

I guess bronze certification only allows for 80% of power or so, which would give me 530W.

Any recommendations of 750W+ PSU?

The used GTX 970 are sold for 20,000 yen but these are from stores. If I were to try to sell it at an auctions, I would probably only get 15,000 yen.

I just called a local PC store who offered me half of that, provided the card was in perfect condition... Quite laughable.

As for the GTX 1070, you are right, it looks like a great card and would be relatively future proof. I found one at 52,000 yen.

Sli gtx970 you are looking at @700w with at least 42A minimum recommendation. That's for a decent psu. While that Lepa technically meets amperage needs (barely) and some would quibble about the necessity for 700 since the cards only pull @150w, what you'll find is that your psu is only good for @2/3rds of its rated power. Pushed close to max, it'll almost certainly fry.

Your best alternative is to try and get $200 for your current gpu, and putting the proceeds plus what you were looking to spend on the extra gpu, towards a better single card that won't tax the psu as hard. Otherwise you for certain if staying with the sli will need to also replace the psu.

Gtx1070 comes in right around the $400 price, ¥50k or so.

 

[David Taquet]

Did my math: even if I sold my GTX 970, it would cost me about 40,000 yen to get the GTX 1070. I found this Cooler Master for 12,000 yen. Another GTX 970 would run me another 15,000= 25,000 yen.

http://www.coolermaster.com/powersupply/gaming-v-sm-series/v750s/

Forgive my noobie question but it mentions "a single 12V rail", is that good or bad? Is it ok for SLI?

 

[Karadjgne]

Couple misconceptions. Your psu is supposed to be capable of delivering exactly what it claims, that being 650w and 45A on the 12v rail(s). However, that number is only certified under certain conditions, namely the psu must be well under 30°C, at sea-level, include high amounts of minor rail (5v and 3.3v) output as well as the 12v output. Unfortunately, this never happens. Most pc's in an environment controlled room of 22°C (air conditioning set at @72ish) will run @30-32°C case temps, before actually seeing any real loading. It's doubtful you are close to sea level, and modern pc's seriously do not use very much 3.3v or 5v anymore, that was out-dated years ago, most of the power comes from the 12v rail. And that's if the manufacturer is actually honest in their claims, many low brands are not. To get honest outputs at rated claims, you really need a quality unit, built by a quality OEM on a quality platform.
https://youtu.be/f6snWfd1v7M
So no, I'd not trust that Lepa unit to deliver anywhere close to its rated 650w and 45A, especially on a modern pc.

80+ is an efficiency certification, its not a standard, it's by a 3rd party who tests and rates psus. The test (mostly) is at 20%/50%/100% loads. To meet 80+ cert. a unit must show 80/80/80 efficiency minimum. 80+ Bronze means it's met a minimum of 82/85/82 and 80+ Gold is 87/90/87. Generally, to meet these levels (assuming they are correct and not a cherry picked psu or outright lie) the psu needs to be better built, have better components and better design. The highest levels being the best built etc. But that in no way affects the actual power capable by the unit, so because you have a Bronze unit, its still supposed to be a 650w, it just has @ 82-85% efficiency when it comes to converting the ac voltage from the wall to usable 3.3-12v DC inside the pc.

A rail is a little misleading. A rail is a series of components that handle the current before output. So a single rail unit, all the current for that voltage is handled by a series of quite large capacity boards and components. In a dual rail, that current is split between 2 such series, that inevitably use slightly less capacity, a quad rail is the same, but 4 such series. Some claim that a single rail is better as there's no gaps, everything coming from one source, some claim that multiple rails are better as the individual rails can handle more current before joining so are more stable, there's no sudden dips if something has a very large sudden draw. Imho, it really doesn't make any real difference, multiple rail psus (the decent or better quality) all start and end at 1 point, they are joined at the output source.

That's a very good psu (CoolerMaster VSM series) btw, better actually than its newer, fully modular brother and won't have any issue with twin 970's

 

[David Taquet]

Wow, thanks for taking the time to answer my questions. It is much clearer now.

I actually spent the better part of yesterday considering my options and it seems that provided I can sell my GTX 970 for a decent price (at least for Japanese standards), getting a used GTX 980 Ti or a used GTX 1070 would cost me about the same. I need to do some more research, which is, I have to admit, half the fun.

Couple misconceptions. Your psu is supposed to be capable of delivering exactly what it claims, that being 650w and 45A on the 12v rail(s). However, that number is only certified under certain conditions, namely the psu must be well under 30°C, at sea-level, include high amounts of minor rail (5v and 3.3v) output as well as the 12v output. Unfortunately, this never happens. Most pc's in an environment controlled room of 22°C (air conditioning set at @72ish) will run @30-32°C case temps, before actually seeing any real loading. It's doubtful you are close to sea level, and modern pc's seriously do not use very much 3.3v or 5v anymore, that was out-dated years ago, most of the power comes from the 12v rail. And that's if the manufacturer is actually honest in their claims, many low brands are not. To get honest outputs at rated claims, you really need a quality unit, built by a quality OEM on a quality platform.
https://youtu.be/f6snWfd1v7M
So no, I'd not trust that Lepa unit to deliver anywhere close to its rated 650w and 45A, especially on a modern pc.

80+ is an efficiency certification, its not a standard, it's by a 3rd party who tests and rates psus. The test (mostly) is at 20%/50%/100% loads. To meet 80+ cert. a unit must show 80/80/80 efficiency minimum. 80+ Bronze means it's met a minimum of 82/85/82 and 80+ Gold is 87/90/87. Generally, to meet these levels (assuming they are correct and not a cherry picked psu or outright lie) the psu needs to be better built, have better components and better design. The highest levels being the best built etc. But that in no way affects the actual power capable by the unit, so because you have a Bronze unit, its still supposed to be a 650w, it just has @ 82-85% efficiency when it comes to converting the ac voltage from the wall to usable 3.3-12v DC inside the pc.

A rail is a little misleading. A rail is a series of components that handle the current before output. So a single rail unit, all the current for that voltage is handled by a series of quite large capacity boards and components. In a dual rail, that current is split between 2 such series, that inevitably use slightly less capacity, a quad rail is the same, but 4 such series. Some claim that a single rail is better as there's no gaps, everything coming from one source, some claim that multiple rails are better as the individual rails can handle more current before joining so are more stable, there's no sudden dips if something has a very large sudden draw. Imho, it really doesn't make any real difference, multiple rail psus (the decent or better quality) all start and end at 1 point, they are joined at the output source.

That's a very good psu (CoolerMaster VSM series) btw, better actually than its newer, fully modular brother and won't have any issue with twin 970's

 

[Karadjgne]

Hah, yeah, it's that 'hurts so good' kinda fun. The more you get into it, the more you want to get, for less. It gets frustrating when something you decide you really want is just out of reach. So... Hmm how do I justify that extra $20...

 

[David Taquet]

True. Here in Japan the second hand market is quite different from the US or Europe. We don't have Craigslist and such (except for cities of 1 million +). So I am comparing auction sites to try and find the best deals. I assume any quality graphic card that hasn't been treated badly is going to last many years, correct?

Hah, yeah, it's that 'hurts so good' kinda fun. The more you get into it, the more you want to get, for less. It gets frustrating when something you decide you really want is just out of reach. So... Hmm how do I justify that extra $20...

 

[Karadjgne]

That's the assumption. Most ppl don't OC their gpus to any degree, because they don't see any difference. Fps in games is so 'up and down' it's really hard to pin down an accurate number. So OC usually isn't a consideration when it comes to abuse. The biggest (imho) consideration is cleanliness. Most grandma's, housewives, non-techy, non-gamer type people have no idea that pc's should be cleaned internally, regularly. Which means gpus are going to suffer. Dust clogged channels promoting overheats, dust clogged fans wearing out bearings etc. So just be careful of who is selling the gpu, and for what reason. The best kind of seller is a kid who is using the proceeds to pay for his own upgrade, he'll probably have a clue about keeping the pc clean, especially if it's on the expensive side.

You've had that 970 for 3 years now? And you are already thinking more power / more performance as games get progressively more intense. With an sli setup, you'll get that, some anyways, especially on dx11 games, DX12 games are iffy as they don't really have support for sli as such, DX12 uses both cards mainly without sli.

But here's the kicker. You'll get on average 0-10 or so better fps with the sli. Depends entirely on the actual game and just how well it's optimized for sli. It's entirely possible on some games that are not fully sli supportive that you'll get worse fps, because the sli is basically acting as a single 970. It's this variety that makes a single, more powerful card more attractive as it performs well over the entire spectrum of games vrs maybe yes/maybe no. In Heaven benchmarks, the sli got almost identical scores to a single 1070, at the expense of a bigger psu, higher heat output, higher noise levels, less efficiency.

Will the 1070 last? Probably as long as 1080p does, several years anyways. Will the 970 sli last? Not as long, it's gonna get cramped by its relatively low vram of 4Gb vrs games that are already using over 8Gb at higher detail settings on higher resolutions at higher refresh.

 

[David Taquet]

You are absolutely right. Also, I may have slightly overreacted about my need to upgrade my GPU. I played ME Andromeda last week and was shocked I couldn't get a stable frame rate even by lowering some settings. Yesterday, I actually realized the game was just poorly optimized and that some mods actually gave an extra 5-8 FPS.
But it is true that I gave my PC all the attention in the world the first few weeks I had it and the took it for granted. eversince. I haven't cleaned it in 18 months, so this will definitely be a priority this week end.
I will keep monitoring the price of the GTX 1070 and check if it would be cheaper to buy it in my home country (France).

That's the assumption. Most ppl don't OC their gpus to any degree, because they don't see any difference. Fps in games is so 'up and down' it's really hard to pin down an accurate number. So OC usually isn't a consideration when it comes to abuse. The biggest (imho) consideration is cleanliness. Most grandma's, housewives, non-techy, non-gamer type people have no idea that pc's should be cleaned internally, regularly. Which means gpus are going to suffer. Dust clogged channels promoting overheats, dust clogged fans wearing out bearings etc. So just be careful of who is selling the gpu, and for what reason. The best kind of seller is a kid who is using the proceeds to pay for his own upgrade, he'll probably have a clue about keeping the pc clean, especially if it's on the expensive side.

You've had that 970 for 3 years now? And you are already thinking more power / more performance as games get progressively more intense. With an sli setup, you'll get that, some anyways, especially on dx11 games, DX12 games are iffy as they don't really have support for sli as such, DX12 uses both cards mainly without sli.

But here's the kicker. You'll get on average 0-10 or so better fps with the sli. Depends entirely on the actual game and just how well it's optimized for sli. It's entirely possible on some games that are not fully sli supportive that you'll get worse fps, because the sli is basically acting as a single 970. It's this variety that makes a single, more powerful card more attractive as it performs well over the entire spectrum of games vrs maybe yes/maybe no. In Heaven benchmarks, the sli got almost identical scores to a single 1070, at the expense of a bigger psu, higher heat output, higher noise levels, less efficiency.

Will the 1070 last? Probably as long as 1080p does, several years anyways. Will the 970 sli last? Not as long, it's gonna get cramped by its relatively low vram of 4Gb vrs games that are already using over 8Gb at higher detail settings on higher resolutions at higher refresh.

 

[Karadjgne]

Online vendors in France are asking €380-€580 for the gtx 1070 atm. That's about ¥47,500-¥72,300

But then again, you could probably pick up a barely used 1070 from someone who just got a 1080ti. At quite a reduced price.