Corsair CX vs RM

Guest · Oct 1, 2014

Soo, I saw these two PSU's, and they both have a pretty significant price differance, with the CX being much cheaper. The RM is more efficient, and its fully modular with flat black cables.

Thats all well and good but do i need it? Which one should I go for, the bronze certified or the gold certified?

Specs:

CPU - i5 4670k
CPU cooler - CM hyper 212
mobo- Asus z97-A
GPU - gtx 770/760 (undecided)
1 HDD
1 SSD
1 optical drive
Case - corsair graphite 230t

Dark Lord of Tech · Oct 1, 2014

Both are poor quality , but go for the RM it's a little better , but not by much.

Shane501 · Oct 1, 2014

What's the wattage and model?

Dark Lord of Tech · Oct 1, 2014

Best 750w on the market , made by Super Flower.

PCPartPicker part list / Price breakdown by merchant

Power Supply: EVGA 750W 80+ Gold Certified Fully-Modular ATX Power Supply (£84.90 @ Scan.co.uk)
Total: £84.90
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2014-10-01 20:10 BST+0100

VincentP · Oct 1, 2014

The Corsair CX series are reasonable power supplies, but they use cheap capacitors that may not last.
The same is true of the RM 750 and 850.
The RM 450, 550 and 650 are much better quality supplies.

This tiered list is a good guide:
http://www.tomshardware.com/answers/id-1804779/power-supply-unit-tier-list.html
The RM 450 / 55 / 650 are in tier 2 class A, while the RM 650 / 750 and CX series are tier 3.
You will also find this backed up by detailed reviews.

Your system requires a 550W power supply, but there is nothing wrong with using a higher rated model if you like.
The RM 550 / 650 are very good.
The XFX TS 550 / 650 are also very good 80 plus gold rated supplies.
Other XFX 550 or 650W models are just as good quality, but 80 plus bronze rated.
The EVGA Supernova B2 750 (80 plus bronze) or EVGA Supernova G2 750 (80 plus gold) are even better quality, but you really don't need this unless they are at a good price.

The difference in efficiency between an 80 plus bronze or gold rated supply will make very little difference in actual power used.
What is far more important is buying a quality supply, and that is why I would recommend any of the supplies above over the Corsair CX series.

Guest · Oct 2, 2014

Thanks for the multiple responses. Call me biased but I really only want to go corsair, and since the rm650 has better capacitors I'll go with that.

Thank you

Guest · Oct 2, 2014

Also, how come the rm750 uses different and supposedly 'worst' capacitors compared to the rm650? Surely the only difference between the two would be wattage?

Beezy · Oct 2, 2014

its probably cheaper to make/use them, thats how the consumer saves.

VincentP · Oct 2, 2014

Companies do the same thing frequently, sourcing different models in the same series from different manufacturers.
I'm sure it is mostly about cost.
The RM 450 / 550 / 650 are made by CWT
The RM 750 / 850 are made by Chicony
That isn't to say the Chicony is always inferior, but in this particular design they used cheap capacitors.
Here is a list of Corsair supplies by manufacturer:
http://www.realhardtechx.com/index_archivos/Page447.htm

Here is one review for the RM 750:
http://www.hardocp.com/article/2013/11/13/corsair_rm750_750w_power_supply_review/3#.VC3UvmeSyao

And this is their comment on the capacitors:
The primary capacitor is provided by Nippon Chemi-con, which is good, but the secondary capacitors are provided by Ltec and Taicon. These are not absolute "no name" capacitors, but these are also not anything near the quality of capacitor we would hope to see in a quality power supply and doubly so when we note how little airflow these will be getting based on the layout of this unit and design of the fan controller.

Here is another review:
http://www.techpowerup.com/reviews/Corsair/RM750/4.html

And their comment on the capacitors:
Our only complaint is the choice of caps in the secondary side. They are not of the best quality, but Corsair seems to trust them since they cover these units with a pretty long five year warranty.

Now a review of the RM 650:
http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story5&reid=363

And theer comments on the capacitors:
Capacitors used on the secondary are a real grab bag. We have one Nippon Chemi-Con on the 5VSB output. Good... you need the good parts there, because they get used all the time, usually with no fannage. Most of the 12V output filtering uses Teapo and Capxon. Not my favorite brands but not the worst. I will have to score on that. Polymers include examples from both Aishi (gesundheit!) and Teapo. I have no quarrel with those. Even the worst polymers seem to hold up better than the run of the mill aluminum electrolytic.

The capacitors that are criticized in the RM 750 and RM 850 come from Taicon and Ltec.
Capacitors in the RM 450 / 550 / 650 that perform the same role come from Teapo and Capxon. Apparently these are better.

Dark Lord of Tech · Oct 2, 2014

They aren't much better , the real good PSU's have 100% Japanese Caps.

Dark Lord of Tech · Oct 2, 2014

For what they charge for RM supplies they should be much better quality.

VincentP · Oct 2, 2014

I'm sure there plenty of tier 2 supplies that do not use all Japanese capacitors.
Not everyone is looking for tier 1 supplies.
While they might be expensive for what you get, the RM 450 / 550 / 650 are better quality than the RM 750 / 850 or CX series.
These deserve to be in tier 2 where they are and should be recommended along with any other tier 2 supply.
Supplies like those from XFX are at least as good and cheaper but they don't have the hybrid fan or modular cables and some people will be willing to pay the extra cost for these.
If I were choosing a Corsair supply, I would prefer the HX series.

Dark Lord of Tech · Oct 2, 2014

RM supplies are way overpriced , just look at the EVGA \ Super Flower models in the same price range , you get top notch quality for your dollar with them.

AX , AXi , HX , HXi are all decent , the rest I wouldn't touch or recommend.

VincentP · Oct 2, 2014

The EVGA Supernova B2 750 or G2 750 are great value.
What do they have to offer in a 550 or 650W model?

Dark Lord of Tech · Oct 2, 2014

Nothing in those wattages which is strange because with the new cards not demanding a lot of power you would think they would have something decent in that range.

VincentP · Oct 2, 2014

This is my problem with recommending anything from EVGA.
The 750W models are fantastic quality and great value if you need a 750W supply.
A 750W supply however is overkill for any single GPU system.
These supplies could power a typical system with an 88W CPU and two 230W graphics cards.
These supplies are perfect for two GTX 970 or GTX 980 cards and any CPU.
The lower wattage models they offer, e.g. the EVGA 600B are not of the same quality (tier 3).

Dark Lord of Tech · Oct 2, 2014

The 500B and 600B are decent FOR BUDGET BUILDS , but I wish they had Super Flower models in a 550w - 650w.

Corsair CX vs RM

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