ATI 4850/4870 voltmod thread

[LuxZg]

I've got an unusual question.

I've got Chieftec 450W PSU (GPS-450AA-101A). Recommendations for 4xxx series are all the way from 400-550W, but we all know they are targeting cheapo chienese PSUs, as I'm seeing much lower total-system numbers in reviews, and people say that even 4850 CF with quad CPU draws like 350W.

So - will I be able to OC 4850 or even 4870? Not going extreme, but I thought about either pencil Vmod for 4850 (under 1.4V probably) or 4870 OCed without voltmods (I've got S1 to chill either of them a bit so temps shouldn't be problem)

Rest of the system isn't heavily loaded but still:
- 1x 250GB Seagate HDD and 1x DVDRW
- 1x 200mm case fan+2x120mm fans (on S1 and Ninja)
- 4x 1GB DDR2 800MHz (@stock)
- E4400 @ 3.2GHz

CPU is currently heaviest load, but I'd rather lower it a bit if it would alow me to get more out of GPU (if PSU is not good enough)

Like I've said, PSU is Chieftec 450W, and says:
+5V=28A, +3.3V=30A (together max 145W), +12V1=14A(168W), +12V2=15A(180W);(these three 440W max); -12W=0,5A(6W), +5Vsb=2A(8W).

So? What do you experts say? Will this PSU take E4400@3.2 + HD4850@1.4V~800MHz or 4870@stock voltage~800MHz? Depending on your answers I'll be picking my card, and means of OCing, so I hope you can help me

P.S. I've seen a guy on OC.uk saying good 450W PSU should be fine even for 4850 CF with Quad CPU, but seeing above calculations about 240% stock wattage scared me a bit, as that's more than 2x in CF :/ Others say 550W for single 4850.. so I'm getting confused :/

[Astennu]

I've got an unusual question.

I've got Chieftec 450W PSU (GPS-450AA-101A). Recommendations for 4xxx series are all the way from 400-550W, but we all know they are targeting cheapo chienese PSUs, as I'm seeing much lower total-system numbers in reviews, and people say that even 4850 CF with quad CPU draws like 350W.

So - will I be able to OC 4850 or even 4870? Not going extreme, but I thought about either pencil Vmod for 4850 (under 1.4V probably) or 4870 OCed without voltmods (I've got S1 to chill either of them a bit so temps shouldn't be problem)

Rest of the system isn't heavily loaded but still:
- 1x 250GB Seagate HDD and 1x DVDRW
- 1x 200mm case fan+2x120mm fans (on S1 and Ninja)
- 4x 1GB DDR2 800MHz (@stock)
- E4400 @ 3.2GHz

CPU is currently heaviest load, but I'd rather lower it a bit if it would alow me to get more out of GPU (if PSU is not good enough)

Like I've said, PSU is Chieftec 450W, and says:
+5V=28A, +3.3V=30A (together max 145W), +12V1=14A(168W), +12V2=15A(180W);(these three 440W max); -12W=0,5A(6W), +5Vsb=2A(8W).

So? What do you experts say? Will this PSU take E4400@3.2 + HD4850@1.4V~800MHz or 4870@stock voltage~800MHz? Depending on your answers I'll be picking my card, and means of OCing, so I hope you can help me

P.S. I've seen a guy on OC.uk saying good 450W PSU should be fine even for 4850 CF with Quad CPU, but seeing above calculations about 240% stock wattage scared me a bit, as that's more than 2x in CF :/ Others say 550W for single 4850.. so I'm getting confused :/

I would not go 1.4v with that PSU. You are talking about increasing the power draw with more then 50 watt. From 1.19 to 1.23 gave me a increase of 25 watt. Stock is 1.14v So i guess we are talking about 230 watt or even more with 1.4v.

You need a good PSU for that. My system only is drawing 380 watt with the 1.23v. And if you have a 450 watt. That not only 12v. Maybe 300-350 = 12v wattage. And the card in 1.4v will draw 230 on the 12v only. And then you still have your cpu and stuff thats also pulling from that rail. I suggest you lower your ambition to 1.2-1.25v or buy a 600 watt + psu.

All the more reason to get the memory running as fast as possible!

Yeah i'm planning on doing the mem mod. To see if i can hit 1175.

Still waiting for that HD4870 1GB or the HD4870 X2 2GB

[LuxZg]

I would not go 1.4v with that PSU. You are talking about increasing the power draw with more then 50 watt. From 1.19 to 1.23 gave me a increase of 25 watt. Stock is 1.14v So i guess we are talking about 230 watt or even more with 1.4v.

You need a good PSU for that. My system only is drawing 380 watt with the 1.23v. And if you have a 450 watt. That not only 12v. Maybe 300-350 = 12v wattage. And the card in 1.4v will draw 230 on the 12v only. And then you still have your cpu and stuff thats also pulling from that rail. I suggest you lower your ambition to 1.2-1.25v or buy a 600 watt + psu.

Ok, so I'm either stuck with BIOS mod (1.21V) or buying non-OC 4870. Though I don't get it - how could this card be pulling this much power (230W over just one 6-pin PCIe connector + PCIe slot?). And I persume my E4400 if clocked down a bit to 2.6/2.8 should be less power hungry than your 5600+ X2..
Bad thing is that for a difference to 600W PSU I'd be spending too much on this whole setup (VGA, PSU, and I still need display as I'm on 17" CRT right now :/ ) grr! Btw, how is it than they run OCed quad+4850 CF with just 335W power droaw (?)