Corsair RMx. Any reason to not buy 850 if it's cheaper than 650?

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Snowdog

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I am wishlisting components for a build. I had kind of settled on the Corsair RM650x, but there is a sale right now, that has the RM750x ($119) and RM850x($129) as cheaper than RM650x($135). (prices are Canadian).

Is there any reason at all to NOT get the 750 or 850 when even the 650 will likely be overkill for my eventual build (6-8 core CPU, single Midrange GPU).

Or is there something better in this price range?
 
The only "downside" to getting either bigger model is you might be in a (very slightly) lower efficiency range, which will never eat up the price difference.

Buy the 750 and enjoy.
 
I have always regretted buying the lower capacity PSU because i didn't need more power. I always end up needing more power. This is likely not true for most people however.
 
Most psu’s now are at peak efficiency and lower temps. Buying more than you need, runs cooler, less noise, and better efficiency.
 
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That would be kind of cool it was essentially a passive PSU, even while gaming.
 
Grebuloner said:
The only "downside" to getting either bigger model is you might be in a (very slightly) lower efficiency range, which will never eat up the price difference.

Buy the 750 and enjoy.
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100% this.
 
I dithered until the 750 went up in price, making the 850 the cheapest model. So I just ordered that one. First component of my next build.

Now if only MSI would bring the Mortar B450 Max to Canada, I'd pull the trigger on everything else. But I may go Intel if I can't get an AMD MB I like.
 
Snowdog said:
That would be kind of cool it was essentially a passive PSU, even while gaming.
Click to expand...

I never saw the fan turn on in my old case where I had the fan facing up and could see it through the window. When gaming or even when running something like Prim95 for 40 minutes. Now it faces down in the new case but I pull the filter every now and then to check on it and there is not even a dog hair on it let alone dust so if must not bet spinning ever. Shit I do not even know if the fan works to be honest.
 
Better to have it and not need it than need it and not have it. Go bigger especially if it's cheaper.

I will toss in a recommendation for the RM850X as that's what I have in my main PC and it's been rock solid for 2 years. On a side note, woah; didn't realize I've had this PSU for 2 years already.
 
jimbob200521 said:
Better to have it and not need it than need it and not have it. Go bigger especially if it's cheaper.

I will toss in a recommendation for the RM850X as that's what I have in my main PC and it's been rock solid for 2 years. On a side note, woah; didn't realize I've had this PSU for 2 years already.
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I have the 850 here now. Though it will probably be a while until I get the components for a build to go with it.
 
Snowdog said:
I have the 850 here now. Though it will probably be a while until I get the components for a build to go with it.
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What's not to like; plenty of power, in my case the fan almost, if ever, turns on since I don't draw all that much from it, and reliable (knock on wood). Hope you enjoy!
 
I've bought the 850. Pretty cool PSU.Actually used in a small mATX case. Vega 64 GPU needed that power I believe.
 
jimbob200521 said:
What's not to like; plenty of power, in my case the fan almost, if ever, turns on since I don't draw all that much from it, and reliable (knock on wood). Hope you enjoy!
Click to expand...

I pulled my bottom filter on my case and there is no dust what so ever on it, so I figure this fan has never spun. That is with a 3900x and 2080 Super video card and gaming. Just a tad bit of overkill but I like it.
 
Jamie Marsala said:
I pulled my bottom filter on my case and there is no dust what so ever on it, so I figure this fan has never spun. That is with a 3900x and 2080 Super video card and gaming. Just a tad bit of overkill but I like it.
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I am planning a lowered powered system, so I was looking at a 650 as overkill, when the sale made them similar price, I bought the 850 for overkill on top of my overkill. :D
 
Yeah I remember a few years ago I was settled on the RM5**X PSU but on the day of buying, the RM650X was just £5 more...RM650X it was.
 
Grebuloner said:
The only "downside" to getting either bigger model is you might be in a (very slightly) lower efficiency range, which will never eat up the price difference.

Buy the 750 and enjoy.
Click to expand...
If it's for your NUC, stick with the 650.
:D
 
Grebuloner said:
The only "downside" to getting either bigger model is you might be in a (very slightly) lower efficiency range, which will never eat up the price difference.

Buy the 750 and enjoy.
Click to expand...
Are you referring to the 850 being gold rated vs platinum rated for the 750? Otherwise, I thought the prevailing wisdom was that between two similar rating PSUs/other things being equal, it is better to buy the one with the higher wattage as it means the PSU will not have to do as much work to provide the power, lowering operating temperatures and increasing efficiency. In other words a 650W PSU supplying power to a system that uses 550W will have to do more work and will lose efficiency over a 1000W PSU. I was actually looking to buy a Seasonic Platinum 1k, to both allow for potential future power needs as well as to not put as much strain on it, but now am curious if that is no longer the best approach. I haven't paid attention to PSUs since Prescott and maybe a little during 1st gen i7 (920) era, so I am not sure if i just read bad info or am out of the loop.
 
ThatITGuy said:
Are you referring to the 850 being gold rated vs platinum rated for the 750? Otherwise, I thought the prevailing wisdom was that between two similar rating PSUs/other things being equal, it is better to buy the one with the higher wattage as it means the PSU will not have to do as much work to provide the power, lowering operating temperatures and increasing efficiency. In other words a 650W PSU supplying power to a system that uses 550W will have to do more work and will lose efficiency over a 1000W PSU. I was actually looking to buy a Seasonic Platinum 1k, to both allow for potential future power needs as well as to not put as much strain on it, but now am curious if that is no longer the best approach. I haven't paid attention to PSUs since Prescott and maybe a little during 1st gen i7 (920) era, so I am not sure if i just read bad info or am out of the loop.
Click to expand...

PSU Gold ratings have a curve to them as far as when they are most efficient. So if you get a 1000 watt PSU and run it on a system that only consumes 200 watts, it could actually be less efficient than a lower wattage PSU. See below graph for what I'm talking about.

80-plus-certification-efficiency-chart.jpeg


So looking at the graph, if you wanted optimal efficiency at 115-120V as we have here in the states, it seems you would want your PSU to be running around 50% of its max rated load. Granted, the differences between 50%, 20%, and 100% aren't day and night but it's good info to have either way. In the pic below, here's that same data in a graph which may be easier to interpret.

Tims-blog3-min.png
 
ThatITGuy said:
Are you referring to the 850 being gold rated vs platinum rated for the 750? Otherwise, I thought the prevailing wisdom was that between two similar rating PSUs/other things being equal, it is better to buy the one with the higher wattage as it means the PSU will not have to do as much work to provide the power, lowering operating temperatures and increasing efficiency. In other words a 650W PSU supplying power to a system that uses 550W will have to do more work and will lose efficiency over a 1000W PSU. I was actually looking to buy a Seasonic Platinum 1k, to both allow for potential future power needs as well as to not put as much strain on it, but now am curious if that is no longer the best approach. I haven't paid attention to PSUs since Prescott and maybe a little during 1st gen i7 (920) era, so I am not sure if i just read bad info or am out of the loop.
Click to expand...

I was not. I think all the RMx's are Gold? You are right, running a PSU around 50% load still remains the best efficiency mark with plenty of overhead for future upgrades and eventual component degradation. For what he was speccing, a 650 was the right size for OP to do that. Moving up to a higher wattage would lower where they are on the efficiency curve by a point or 2, but the cost savings of the higher-wattage PSU was more than would ever be spent on the extra electricity it was going to use due to that.
 
jimbob200521 said:
PSU Gold ratings have a curve to them as far as when they are most efficient. So if you get a 1000 watt PSU and run it on a system that only consumes 200 watts, it could actually be less efficient than a lower wattage PSU. See below graph for what I'm talking about.

So looking at the graph, if you wanted optimal efficiency at 115-120V as we have here in the states, it seems you would want your PSU to be running around 50% of its max rated load. Granted, the differences between 50%, 20%, and 100% aren't day and night but it's good info to have either way. In the pic below, here's that same data in a graph which may be easier to interpret.
Click to expand...
Wow, good info. I am waiting on the Ryzen 4000 series to build my next rig, but was debating on going ahead and grabbing a 1kW PSU now. Maybe i should wait a bit to make sure that even makes sense.
 
If you are able to get a good psu with more wattage i would do it. Just gives you more room in the future in case you upgrade cpu or gpu on your next build.
 
ThatITGuy said:
Wow, good info. I am waiting on the Ryzen 4000 series to build my next rig, but was debating on going ahead and grabbing a 1kW PSU now. Maybe i should wait a bit to make sure that even makes sense.
Click to expand...

Also keep in mind today's electronics have lower idle power draw than ever. Partial core shutdown, low idle voltages, and more mean that a 600 watt system can easily idle under 200 watts, if not less than 150.

Wait until you find a good PSU for a good price. With SLI/crossfire all but dead, a gaming system really doesn't need more than a 750 watt PSU. It's a different story if you're going Threadripper and using it for CPU intensive tasks.
 
For PSUs of similar quality more is better unless budget breaks it. And in this case you are looking at cheaper ones with more watts anyway. Not downsides as far as I can see
 
Wooshoo said:
For PSUs of similar quality more is better unless budget breaks it. And in this case you are looking at cheaper ones with more watts anyway. Not downsides as far as I can see
Click to expand...

Except that I jumped the gun, have a PSU and my build my be on hold. I might get a gaming laptop and hold off on the build for quite a while.
 
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