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Thread: 650W/750W PSU

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    Post 650W/750W PSU

    Greetings, Earthlings!

    Some equipment on my mothership needs replacement but I'm too away from home so I need to get a few parts here on Earth. I've found out that this forum is one of the best ones so I decided to stop by on the way - maybe you will be able to help me with providing some answers to a few questions?

    I'm looking for the most suitable PSU for this configuration: i7-6700K, Asus Z170 Pro Gaming, MSI Gaming X 1070 (or 1080, not decided yet), 2x DDR4, SSD/HDD/DVD, 4x fan.

    My current plan is (as always in the past): do not do any custom OC right on start, do some OC after 2-3 years (when applications will become more demanding), after 4-5 years: replace graphics card (or add another one to create SLI*), after 8-10+ years: buy another equipment.

    *) At this time, replacing a card is probably a 95% sure thing but SLI option is nice to have "just in case".

    I want to have a modular PSU with fanless mode used as often as possible. Most of PSU calculators suggest 650W - but I am not so sure if it is enough for SLI option in future (even if it is less likely to be true).

    Here are a few PSUs I found at almost the same price (+reviews from this site):
    - Corsair RM750i (review here)
    - EVGA SuperNOVA G2 750W (review here)
    - Super Flower Leadex II 750W (no II review, Leadex version review here)
    - Seasonic Prime 650W Gold (no Gold review, Platinum version review here)

    Most noticeable fact is that three of them are 750W at this price. Seasonic is the only one with 650W and the smallest one. All of them have fanless mode but "out of the box" only Seasonic recommends "fan facing up" intallation (including proper orientation of labels on PSU case) - anyone knows why? Also some Seasonic reviews claim that Seasonic's cables do not have build-in capacitors - I'm kind of confused at this subject, is it bad or good (good because of better results, but can be bad for cable placement).

    The only Seasonic Prime 650W Gold test I found is at this Danish website and the results are quite nice, so now I'm biased towards Seasonic but I really miss that 100W that will/could be useful in the event of second card possibility (but what if not...).

    The question is: what would you recommend to me and why?

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    PSU Calculators are Bullshit most of the times. Especially if you add more than CPU and GPU.

    What you really need for that setup is a good quality 400W PSU. Since there are not many a 500 or 550W would be a good choice too. No need for a 750W one!!

    That's something you might want to think about if you have more than one Ultra High End GPU (ie Radeon FUry X, GF1080 TI) with at least 250W TDP...

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    Quote Originally Posted by Lexxor View Post
    only Seasonic recommends "fan facing up" intallation (including proper orientation of labels on PSU case) - anyone knows why?
    TTBOMK it's just marketing gimnick: it's somewhat irrelevant how you will mount any PSU.

    BTW, Seasonic has more detailed info on their website: as you can read there, you can mount the PSU as you want without penalties, and preferred orientation is mostly a marketing gimnick, likely aimed at pleasing those nitpicky enthusiasts who apparently care about how thermal convection works (but in an erroneous/oversimplified way).


    Quote Originally Posted by Lexxor View Post
    Also some Seasonic reviews claim that Seasonic's cables do not have build-in capacitors - I'm kind of confused at this subject, is it bad or good (good because of better results, but can be bad for cable placement).
    It's another marketing gimnick, neither good or bad but, without caps, cables may be sometimes a bit less stiffy to route.


    Quote Originally Posted by Lexxor View Post
    The question is: what would you recommend to me and why?
    Corsair RM550x, or if you wanna spare some money, Bitfenix Whisper M 450W: bottom line could be something like a Corsair Vengeance 400 or a Be Quiet Straight Power E10 400W.

    Why? Because 550W is enough for a SLI of 1080, and the other ones are enough for whichever single GPU.
    Best, Luca

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    Quote Originally Posted by Stefan Payne View Post
    That's something you might want to think about if you have more than one Ultra High End GPU (ie Radeon FUry X, GF1080 TI) with at least 250W TDP...
    All good quality PSUs have 10+ years of guaranteed use, so I'd like to buy a PSU which will be ready enough for some equipment changes across such or similar period of time. Yes, I know, we can not predict the future, but it is much easier for me to buy a little bigger unit now (and have some power reserve) than to replace whole PSU later.

    Quote Originally Posted by quest for silence View Post
    TTBOMK it's just marketing gimnick: it's somewhat irrelevant how you will mount any PSU.
    Yes, I know that both variants will work for all PSUs. But (by looking at physics and the way how hot air "works" = going up) if we are looking at PSUs with semi-fanless mode (such as these I mentioned) then mounting them with fan facing up should make them work longer without turning their fan on, am I right?

    Quote Originally Posted by quest for silence View Post
    It's another marketing gimnick, neither good or bad but, without caps, cables may be sometimes a bit less stiffy to route.
    Yes, that's for one - without caps cable routing could be a little easier. Another thing is modding - you need dedicated solution for such cable with caps if you want to replace it and keep parameters of the system at the same time.

    Quote Originally Posted by quest for silence View Post
    Corsair RM550x, or if you wanna spare some money, Bitfenix Whisper M 450W: bottom line could be something like a Corsair Vengeance 400 or a Be Quiet Straight Power E10 400W.
    As I mentioned earlier, I'd like to have PSU's fan off for the longest possible period of time - doesn't lowest possible PSU's power go against my idea?

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    Quote Originally Posted by Lexxor View Post
    Yes, I know that both variants will work for all PSUs.
    Your start let me think you didn't read the Seasonic link.


    Quote Originally Posted by Lexxor View Post
    But (by looking at physics and the way how hot air "works" = going up)
    That's why I wrote against about oversimplifying, in my previous post: broadly speaking, that's not true.
    Still broadly speaking, it *may* happen just when there's no active/forced airflow in the case and some form of stack effect is implemented.
    Otherwise air recirculation is mostly caotic.


    Quote Originally Posted by Lexxor View Post
    if we are looking at PSUs with semi-fanless mode (such as these I mentioned) then mounting them with fan facing up should make them work longer without turning their fan on, am I right?
    No: in a contemporary tower case, the most probable effect is that the PSU will heat up the GPU. In different cases, YMMV.


    Quote Originally Posted by Lexxor View Post
    As I mentioned earlier, I'd like to have PSU's fan off for the longest possible period of time - doesn't lowest possible PSU's power go against my idea?
    Well, I myself was a little sloppy, I beg your pardon for TL;DR.

    Going fanless is something you want in order to lower the overall noise floor.
    But lowering the overall noise floor often doesn't require a fanless cooling, which may also be counterproductive because of some form of electronic noise (sometimes referred as coil whining).

    Said that, with reference to the PSUs you quoted, the Leadex II (given the increased power density), has a more conservative cooling (so a reduced fanless operation) and it's not a good candidate by any meaning in order to build a really quiet rig.
    Even the Seasonic Prime Gold doesn't look a good candidate due to aggressive cooling and nasty fan sound signature (some more info here).

    All in all, the older RM750i and 750 G2 are clearly a safer bet, IMO.

    At the same time, they are not free of doubts. The RM750i digital fan controller exhibited a weird behaviour in the only known extensive noise testing (on Tom's Hardware Guide), while the current G2s are no more built directly by Super Flower (they were outsourced for economical reasons), so the relevant QC (quality control) may be lower.

    Out of your candidates, you should ask to yourself when you want your PSU operates fanless.
    With reference to a GTX 1070 rig, the expected gaming power draw is in the 240W ballpark (270W for a GTX 1080 equipped rig).

    Is a 240W / 270W fanless operation range within the RM550x capability? Yes.
    So no need to spend anything more.
    Is a 240W / 270W fanless operation range necessary? No.
    At 240-270W your cooling system would be already screaming, so all you really would need it would be a gentle PSU fan ramp up (the only possible exception could be a not air-cooled, properly setup GPU).

    So, is the largest/longest fanless operation range really desiderable? IMO definitely no.

    If you are aiming at a very quiet operation for such a rig, if your PSU should last ten years or more, personally I won't require a mandatory semi-passive operation, and I'd think at first glance to something like a Be Quiet P11 550W, a Corsair RM550x, and eventually to a Super Flower Leadex Platinum 550W or a fully passive Super Flower Golden Silent 500W. The only overkill I'd think to, it could likely be a Seasonic Prime Titanium 650W.

    IMHO second best are the EVGA P2 650W / Super Flower Leadex Platinum 650W, and third place to the PSU you quoted: but in this respect I guess many other trade offs are possible.

    Hope this helps a bit more than my previous post.
    Best, Luca

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    Seasonic makes actual fanless PSU's that go up to 520 watts, more than you will need to run your rig. If you are concerned about cooling you can put a 500 rpm fan at the grill face of the PSU and feed it air quietly -- so quiet you will never hear it, even if your GPU fans are not spinning.
    CPU: Core i7 8700k, HT enabled, all 6 cores OC'd to 4.8GHz, Vcore = 1.24v
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    RAM: 4x16GB (64GB) Corsair Vengeance LPX DDR4 RAM 16-18-18-36@3200MHz, Vdimm = 1.35v
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    HD: WD 500GB (old); Case: LIAN LI PC-7H Aluminum ATX Mid Tower
    PSU: Seasonic Platinum 660W

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    Quote Originally Posted by Lexxor View Post
    All good quality PSUs have 10+ years of guaranteed use, so I'd like to buy a PSU which will be ready enough for some equipment changes across such or similar period of time. Yes, I know, we can not predict the future, but it is much easier for me to buy a little bigger unit now (and have some power reserve) than to replace whole PSU later.
    And why do you think the Power consumption should increase ever again?!
    Especially since the cost per transistor doesn't really go down anymore...

    Take a look at modern graphics cards. At modern CPUs. And how low their power consumption is. And for the money you NEED to get a system that comes close to 600W primary. You need at least ah HEDT system like LGA2011 or the upcoming AMD Threadripper and LGA2066. And you probably don't want to pay for that.

    The same goes for the graphics cards.
    To be blunt: The lower end things became mid range, mid range became high end with this generation. And thus the power consumption was greatly reduced. And modern mid range GPUs only have ONE (8pin) connector.
    So here again, you have to pay a lot of money to get a graphics card that really pulls a bit out of the PSU...

    Together with the HEDT system we are talking about 1500 (more like 2000-2500) bucks for one GPU - and even then it's hard to get more than 400W on the plug from the PSU, without overclocking of course...

    Are you THAT rich to pay for such a system?!

    Quote Originally Posted by Lexxor View Post
    Yes, I know that both variants will work for all PSUs. But (by looking at physics and the way how hot air "works" = going up) if we are looking at PSUs with semi-fanless mode (such as these I mentioned) then mounting them with fan facing up should make them work longer without turning their fan on, am I right?
    No, because there are PSUs that use the backside of the case as a heatsink. The Seasonic ones for example. Even KM3. Don't know about Prime though.

    Quote Originally Posted by Lexxor View Post
    As I mentioned earlier, I'd like to have PSU's fan off for the longest possible period of time - doesn't lowest possible PSU's power go against my idea?
    PSU Fan Off is just bullshit.

    You want to not hear the fan at all if you are at a reasonable distance. If you have a decent quality fan without any noticable bearing/motor noise, what's the point in switching it off? Right, Marketing. I hate things that don't make any sense...

    If you really want a quiet unit, Cooler Master V-Series and be quiet Straight and Dark Power Pro Linup is a good choice. High End Corsairs may also be a decent choice. And low watt Bitfenix Whisper M. The 850W is also a bit on the higher side -> ~670rpm.

    As for the Seasonic Prime: There are some mentions of bearing/motor noise from the fan. One person had 4 Primes (3 Gold, 1 TItanium) and they weren't that good. Others seem to report the same in German forums. So that isn't an option for someone who wants a silent unit.

    I'd say the same about the units Super FLower makes. The fan is OKish in terms of noise, but the fan RPM is on the higher side. You can expect something around 700rpm, with the 1kW even more. So not that great for the 650/750W Leadex II...
    Platinum can be a bit less noisy, still not one of the better ones...

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    Well, there are so many interesting facts I didn't know about, thank you for them - but, on the other hand, they made my choice so complicated now...

    Quote Originally Posted by quest for silence View Post
    Even the Seasonic Prime Gold doesn't look a good candidate due to aggressive cooling and nasty fan sound signature (some more info here).
    Quote Originally Posted by Stefan Payne View Post
    As for the Seasonic Prime: There are some mentions of bearing/motor noise from the fan. One person had 4 Primes (3 Gold, 1 TItanium) and they weren't that good. Others seem to report the same in German forums. So that isn't an option for someone who wants a silent unit.
    ...and I thought that getting Seasonic would be a very safe bet... :/

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    Don't go for a fanless mode. When it is needed the fan tends to surge on. A PSU with a quiet fan is . . . quiet, and ramps up quietly. Or you can go with a fanless PSU. More expensive, but Seasonic makes good ones. As a matter of fact, most people don't need as many watts as you can get from a fanless. If you must have airflow, get a silent fan (equal to or less than 500 rpm) and blow it into the face of your fanless psu. That way you can rest assured that your psu will never make much noise.
    CPU: Core i7 8700k, HT enabled, all 6 cores OC'd to 4.8GHz, Vcore = 1.24v
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    PSU: Seasonic Platinum 660W

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    One more candidate to buy: EVGA GS 650W - what do you think about it? Is it still made by Seasonic?

    This PSU was suggested by my two friends as they bought it a few months ago for quite similar PCs, no visible problems so far.
    Last edited by Lexxor; 05-27-2017 at 11:43 AM.

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