I am going to get a new HD4850, but before proceeding with it I did the research to see if my power supply can handle it.
Even after all the readings I did, I am still not confident, so I want to check it up with the community. Here is the situation with
my current PSU.
Brand: LC Power
Product code LC6550
Continuous power 550 W
Max. current 12 V - Rail 1 16 A
Max. current 12 V - Rail 2 18 A
The following tests were done on the 12V rails :
Measured voltage 12V1 rail
4 A load (= 50 W @ 12 V) 12.15 V
8 A load (= 100 W @ 12 V) 12.03 V
12 A load (= 150 W @ 12 V) 11.93 V
16 A load (= 200 W @ 12 V) 11.83 V
20 A load (= 250 W @ 12 V) 11.75 V
24 A load (= 300 W @ 12 V) 0
28 A load (= 350 W @ 12 V) 0
32 A load (= 400 W @ 12 V) 0
36 A load (= 450 W @ 12 V) 0
40 A load (= 500 W @ 12 V) 0
Maximum load 12V1 (+3/4) within 5% margin : 21 A
Measured voltage 12V2 rail
4 A load (= 50 W @ 12 V) 12.09 V
8 A load (= 100 W @ 12 V) 11.94 V
12 A load (= 150 W @ 12 V) 11.82 V
16 A load (= 200 W @ 12 V) 11.71 V
20 A load (= 250 W @ 12 V) 0
Maximum load 12V2 within 5% margin 18 A
So on Rail V1 there are 21 A at maximum load, and as far as I know, HD4850 requires at least 18 A. Also, the PSU is listed at
over 80% efficiency, but I had it for about two years now and if I am not mistaken, over time, the capacity drops due to
wearing down of the component. Now, I have calculated total Watts usage and that should be fine, but I am concern about
not providing an extra amperage to the rail so that the card can run without having to starve for power.
If someone could shed a bit more light if my concerns are adequate? Especially the two-rail thing is not completely clear to me,
basically does this means that if needed the combined can be supplied to one of the rails, or the 21A max is all there is to the V1 ?
Sounds good enough. Mind if I ask also this - the techie guy at the store implied that I am better off ordering a HD4770 since
the price difference is larger and the difference in performance is not as big. Is that plausible ? I saw a few benchmarks here
and there, and seems 4770 is not as persistent in general. On some bench it beats its NVidia counterparts and even the 4850,
and on some is on-par with the 4830.
I knew that would happen, always the techie guy at the store messes up with my pre-made plans!