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| Thread ID: 67218 | 2006-03-21 09:11:00 | PSU question | SKT174 (1319) | Press F1 |
| Post ID | Timestamp | Content | User | ||
| 439688 | 2006-03-21 09:11:00 | Some display cards requires or says it need to have a minimum of 22A on the 12v rail in a PSU. I've noticed some good quality PSU contains two 12v rails and some even have three 12v rail in them. The question is ... If a PSU says it has two 12v rails and distributed as 20A on 12v1 and 21A on 12v2, does it mean I have 41A in total? Another PSU says it has three 12v rails as 12A on 12v1, 22A on 12v2, 14A on 12v3, again, do I have 48A in total? Is a three 12v rail PSU better than the one that has only two ? What would happen if the PSU doesn't have the power the display card requires? Will it just perform slower or it will do something strange under heavy load? Like make the machine hang...etc.? |
SKT174 (1319) | ||
| 439689 | 2006-03-21 11:25:00 | Useally on bootup a message well come up saying there is insufficient power to run your video card. The extra lead is needed to run the fan on the video card. You just plug one of your spare HD/CD rom power leads into it. Trevor :) |
Trev (427) | ||
| 439690 | 2006-03-21 11:58:00 | You don't need 22A of 12v just to run a fan. SKT174, you have to be careful with PSU claims. Some ratings just mean that you can draw up to X amps on a lead so long as the total load on the other leads doesn't exceed some other value. |
PaulD (232) | ||
| 439691 | 2006-03-21 14:05:00 | I myself have a two 12v rail PSU, I guess 3 Rail would be better (more stability - dedicated supply to CPU, Drives and Videocard/s) When a video card says it needs at least 22A, that would be total 12v output of the PSU, if you had only one 12v rail. (you wouldn't need 22A for the card, but you'd want at least that to power the card and the rest of the components of a typical computer happily) Obviously if you have a 3-rail PSU which totals 48A, It would be enough!! In my experience with my own nvidia card, if it's not getting enough power the drivers will alert you on startup, and the card will run at low power mode to prevent damage. I still wouldn't want to run it in this state very long. I don't know about ATi cards but I guess they would have a similar feature. |
Agent_24 (57) | ||
| 439692 | 2006-03-21 21:02:00 | If a PSU says it has two 12v rails and distributed as 20A on 12v1 and 21A on 12v2, does it mean I have 41A in total? Is a three 12v rail PSU better than the one that has only two ? What would happen if the PSU doesn't have the power the display card requires? Yes. No, not if you had a low quality PSU. It won't work. |
pctek (84) | ||
| 439693 | 2006-03-21 21:31:00 | If a PSU says it has two 12v rails and distributed as 20A on 12v1 and 21A on 12v2, does it mean I have 41A in total? Unlikely. There is an Antec with 2 12V 19A rails but there is a limit of 530 watts total so you could get 19A from each only if all the other rails were under 80 watts. Another example that is easier is the Enermax ELT500AWT 2 x 22A 12v but limited to 30A of 12v not 44A. |
PaulD (232) | ||
| 439694 | 2006-03-21 22:26:00 | Thank you guys, it cleared a lot of things up for me. :thumbs: |
SKT174 (1319) | ||
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