Suitable replacement for Corsair RM850?

Hardware PSU
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Hi, I’ve got a pretty old monster PC here (2011/12 vintage, I think, but not 100% sure of the date as I acquired it from a friend). It packed in the other day.

I had just updated the BIOS (successfully, it seems, as the problem didn’t start at that point), and then had configured a RAID1 combination of two identical sized hard drives. Immediately after configuring the RAID (correctly, as far as I can tell, but not sure as I’ve never done that before), the PC failed to start properly.

What it’s precisely doing is that it starts for a few seconds, the fans come on, and whatever else, and then it stops. Immediately it starts again, and the same thing over and over and over. It doesn’t allow me to go into the BIOS at all. I’ve searched a bit, and done what all the advice says - I disconnected the hard drives and anything else that might be messing with things, including the graphics card (but not sure if I’m supposed to do that!). That didn’t change anything. I read somewhere that the problem might be caused by the power button and not the supply, but no idea how I could figure that out. So anyway, is there any way of knowing 100% for sure that it’s the PSU which is the problem, and if it is, are these (link below) the correct replacements? The name’s the same, but is it still the same thing??? Sorry, I don’t have much confidence about these things!

https://www.amazon.co.uk/s?k=corsait+rm850&i=computers&ref=nb_sb_noss_2

Of course I’ve been thinking about building a new PC for a while already, but it will be my virgin experience so there’s been a certain amount of hesitation, and anyway given the crazy prices of some components at the moment, most obviously graphics cards, I’d prefer for now to squeeze a little more out of what I’ve got, on the assumption that I could transfer a new power supply to a new PC when (or if!) prices hopefully normalise a bit.

OK, that’s enough for now. Thanks in advance, as ever!

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Honestly just get something with a good warranty that meets your power needs. I prefer Seasonic, but honestly it doesnt matter.

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Out of interest, what case is it? It does sound like the power button might be sticking.

I’ll echo what Mutation said. I mostly just stick to looking at Seasonic, Corsair (avoid the cheaper units), Be Quiet, Fractal Design, and Cooler Master.

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Aha, the case. That is a good question, and I’m afraid I really don’t know the answer, because like I said I got the thing from a mate. I can’t see any brand name. I can say that it’s a proper monster, but all I can see to identify it is this label on the bottom of the case, which is probably no help whatsoever :smirk::

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I’ll add one little thing that makes me think that the malfunctioning power button theory might have some relevance. The computer has/had a habit of starting itself up out of hibernation without me ever touching anything, even when keyboard and mouse were both switched off. I checked all the relevant issues that Windows might have been causing, but that didn’t get rid of the problem completely. Not sure if that has any bearing, though?

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If you want to test the case power and reset buttons, you can disconnect them and use one of these in its place:

Check first if there’s a power button on the motherboard itself, in which case those are unnecessary.

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Disconnecting unnecessary components for testing is a good idea. If you know that both the motherboard and the cpu support integrated graphics, then you can remove the GPU and connect the monitor to the video output on the motherboard i/o panel. If not, you’ll need a video card to see the bios of course. Otherwise you really only need motherboard, cpu, ram, and power to those components.

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Side note, if you’re using the motherboard’s raid feature, to my knowledge it’s generally considered inferior to software solutions, so typically you should use your OS to form the raid array unless you’re using a pci raid card.

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When buying a PSU as mentioned above you’ll want to stick to a reputable brand. Ideally you should look up reviews for the specific models you’re interested in (e.g. JohnnyGuru and Aris from tomshardware are two highly trusted reviewers, and I’ve heard LTT has a PSU tier list which may be useful), and know that quality can vary not only between models from the same brand, but even between different wattage levels of the same model.

That said, you can usually just get any model from a good brand with a good warranty and not have to worry about it. For Corsair all of RM HX AX are excellent, I think TX is ok, CX is junk. To Zavar’s list I would probably add Antec, and only specific lines of EVGA Gold PSUs (probably only G1+, G2, and maybe G3; I’d avoid others).

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Thanks very much for all that! I can’t see any sign of a power button on the motherboard, but maybe I just don’t know exactly what I’m looking for. Anyway, I’ll try the power button checking first. Is this the same as the stuff you linked to?

(cheaper, plus I try not to buy too much from Amazon!)

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Pricing hasn’t been too dumb, for more conventional power outputs [maybe with exception of 850 at times, before going 4 digit territory]. Power efficiency and modularity, dependent on brand, can dictate how long term warranty support goes on for

Small ex.) Seasonics 850W Gold Rated
Semi-modular [24pin / EPS 8pin / 2xPCIE 8pin fixed] = 7Yr; Full-modular = 10Yr [at ~20diff]

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Sometimes it’s just a simple button like this
image

And sometimes it’s more pronounced like this
image

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I can’t find any mention of such a button in the manual. Do they all have one, or is it perfectly possible that this one doesn’t? I’ll have another look at the board in a bit, but my tired eyes aren’t up to the task just now!

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No not all boards have built in power buttons. Most just have the pin headers for the switch to plug into.

Now this may or may not put you out of your comort zone but you can just short the two pins that you plug the cases power button to with literally anything metal and it will turn on the PC.

I do this when building and testing outside a case just with a screwdriver. You just touch it to the two pins and it starts.

Be careful which two pins though, it has to be the two for power.

They look something like this. And are usually along the bottom of the motherboard.

Just saves spending money and waiting for delivery

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Definitely well out!side mine! But thanks for the suggestion, of course.

I think I’m better off buying a power switch if there’s no button on the board. Just for confirmation, these ones on ebay will do the job? They’re super-cheap, and I’m OK waiting a few days.

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Yes those will do fine

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Cool, thanks, I just went ahead and ordered them :+1:

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Overall, most name brand PSU’s are decent. If you do look at the resources posted the better OEM’s are SuperFlower, Seasonic and FSP. Almost all the name brands except for Seasonic don’t manufacture their own products. And it will come down to models, not just the overall line. A quick rule of thumb is look at the warranty. The 10 year warranty is hard to beat and is a pretty good indicator of quality. Don’t accept anything less than a 5 yr. Stay away from Gigabyte! Don’t overbuy either. Add up your wattage carefully. If a 550W will do, don’t bother with the 850W. This PSU could be going with this system. Intel is pushing a new standard after 15 yrs and these current PSU’s may be going away if you eventually buy a modern system.

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Well, thanks Everyone. I got a bag of the cheap and cheerful switches, and tried testing with one of them, unplugging everything apart from the motherboard. And the same thing is happening. So does that conclusively mean that it’s the PSU, and there’s nothing else to test for?

The PSU that I’ll be replacing is 850W, so I assume that I can’t get anything less than that. I wouldn’t know how to add up all the wattage, to be honest, since like I said I got the thing from a friend, but I assume that 850W is on the maximal side anyway, right? If it’s too much I won’t worry about it too much, as I may well use it when I build something in the future.

Seasonic seems to be the most popular name that I’ve seen in your replies, so should I assume that any of these would be OK? (not the one that is 2.5 times the price, of course!)

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Hi, I’ve bought the Seasonic PSU as mentioned in the previous post, and done my best to plug everything in correctly (and bear in mind that this is my first time delving all the way down to these cables).

Well, exactly the same thing is happening now as before. A few fans come on for a couple of seconds, turn off and start again. A light on the DVD drive flickers on for a few milliseconds, and also something on the CPU fan. But not much noise of hard disks spinning, as far as I can ascertain.

What do I do now??? Do I now just assume that it’s the motherboard? Is there some basic rookie error that I’m committing with the cables? I’m at the absolute limit of my knowledge here. At this point, how do I even know that the old PSU was worn out? Please don’t disappear now guys. I have invested.

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