A safe PSU/video card combo?

[Edward Yee]

Decided to upgrade incrementally, so I'm now running the MSI R5770 HAWK, but I've read something about it wanting/needing at least 36A on the 12V rail, but my Ultra LSP550 apparently has only 30A on the +12V rail... on the other hand, at least at light load (or idle?) the system's so far running stably. Do I have to run out for a new PSU? (If so, most likely pick would most likely be the LSP650 with a claimed 38 A on +12V.

Also considering an AMD quad-core, but when I see wattage (currently using a AMD dual-core 45 W) and references to "thermal design power," how much does that directly affect power consumption? I ask this because it seems that 45 W = a huge premium in terms of price, and I'd have more -- and probably cheaper up front -- options if 95-125 W doesn't necessarily = huge electric bill. (It seems that there's no 65 W or 80 W AMD quad-cores.)

[starslayer]

TDP is what the processor will output when put under full load (100% utilization on all cores); since most of the time you aren't running at full load, the processor will not suck down its TDP - not even close. The more powerful a processor is, generally the higher its TDP.

I have never heard of that PSU, and I do not know the quality associated with the brand. Still, I doubt you need 36 A (or even 30 A) on your 12 V rail to run this thing. What are the rest of your system specs?

[Edward Yee]

The CPU is an AMD Athlon X2 5000 series (64-bit, 2.6 GHz, 1 MB L2 cache, 65 W, Socket AM2), the motherboard is Gigabyte GA-MA780G-UD3H (using the AMD 780G chipset, supposedly Socket AM3+ Ready), 4 GB RAM (240-pin DDR2 from OCZ). Hard drive is a Western Digital SATA-type at 7200 rpm, and there's a pair of Asus DVD burners. The case (mid-tower?) has a 120 mm intake fan and three exhaust 80 mm fans (one side panel, two rear).

I understand that right now that's (up to?) 120 W for the video card overall, so I'm hoping that I have some head room when it comes to upgrading the CPU, assuming a situation where CPU and GPU usage are somehow maxed (hitting that TDP wattage) -- I don't intend to OC, if that helps.

[starslayer]

Even running everything flat out, you won't be hitting 30 A on your 12 V rail with that setup. If you throw in a Phenom II or something, it will, but again that's only with everything running at capacity. If you decide to get a new CPU, you may want to look for another 500 or so watt PSU that offers about 35 A on the 12 V rail to keep efficiency up; PSU's are generally most efficient when dealing with a load that's about 50-75% their rated wattage, and with the Phenom, your system would be sucking down around 350-400 W at load.