Confusion on Amp on the +12 Volt Rail

[McNuggz]

Hello guys, I'm a newbie to power supplies and I'm not sure what the numbers on the power supply sticker I have mean and whether or not I have a bad power supply or not. It's a 220W power supply from some chinese company that I've never heard of before and its from an hp slimline pre-built. From the description it sounds like it's a pretty terrible quality psu, but I don't know for sure since I don't know the +12 volt current rating of it (not sure if I used the correct term there). It has +12Va and +12Vb on it with 8A for a and 16A for b and it says the total of the two is 204W. But since it has +12V a/b I don't know the actual volt current rating in amps it has, and my two main questions to that are:

1. Are the amps combined or are they split and how does that affect the power that goes to my GPU?

2. Besides the 220W, is the power supply terrible and I should get a new one or is the volt current rating sufficient enough to handle my pc with my graphics card? (I'm not planning to upgrade the gpu I have, though I have seen a 750 Ti within an HP compaq with a 240W PSU)

3. Less important but, how much more power does my gpu draw if I increase the core clock by 220 Mhz from 901 Mhz?

My specs are: Pentium G640 (65W), EVGA GT 730 2 GB GDDR5 64-Bit Overclocked +220 Mhz Core +400 Mhz Memory (25W), 6GB DDR3 1066 Mhz RAM (4+2GB), 1 TB 7200 RPM Toshiba HDD, One 80mm or 120mm (not sure which it is) Case Fan, Logitech G302 Deadulus Prime Gaming Mouse, Logitech Speakers, HP Keyboard, Foxconn Joshua-H61-uATX Motherboard and a DVD Burner Drive. I included all the things plugged in too since I'm pretty sure those add additional power to the pc. Additionally I've been using the same PSU with my overclocked GT 730 for a month and a half now and I've had no issues.

Link to the image of my PSU sticker: http://imgur.com/a/kfOQi

 

[techgeek]

You have it right there in your explanation. A and B are "separate" rails, A is providing 8A of current, and B is providing 16A of current. It means that it can supply up to 8A of current on A "or" up to 16A of current on B. It can't supply the total 24A as that would be 288W (Voltage X Current) which isn't possible. It can provide "up" to a total of 17A on the two rails as long as rail A doesn't exceed 8A. To further obfuscate things is the total power the 12V can supply your system drops as you increase the load on 3.3V and 5V rails. So if you are say supplying 20W total from those two rails, then the PSU can only supply 190W max on the 12V rails. Fortunately most systems draw most of it's power from the 12V rail.

 

[McNuggz]

You have it right there in your explanation. A and B are "separate" rails, A is providing 8A of current, and B is providing 16A of current. It means that it can supply up to 8A of current on A "or" up to 16A of current on B. It can't supply the total 24A as that would be 288W (Voltage X Current) which isn't possible. It can provide "up" to a total of 17A on the two rails as long as rail A doesn't exceed 8A. To further obfuscate things is the total power the 12V can supply your system drops as you increase the load on 3.3V and 5V rails. So if you are say supplying 20W total from those two rails, then the PSU can only supply 190W max on the 12V rails. Fortunately most systems draw most of it's power from the 12V rail.

Thank you for the fast response. If I understand correctly, the most it can provide is 17A on the +12V but I'm wondering if that's enough if the minimum PSU requirement is 20A on the +12V.

 

[techgeek]

Is the 20A requirement a requirement of your GT730? These "requirements" are often fairly conservative. Often they use worse case scenarios when estimating the GPU + system 12V requirements.

That said OEM's bid out PSU's on lowest cost per unit. That doesn't make quality the highest priority. Most often there is very little overhead in OEM PSU's above the base system requirements. If you aren't experiencing issues yet, you "might" be OK for awhile. However a decent 300W or slightly better might be more advisable.