700mhz wall on HD4850 is smashed.

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07-08-2008, 10:06 PM
Devious

Quote:

Originally Posted by ghost101

I think its possible that the 150w supply via the pci-e slot and pci-e 6pin isnt enough. 150w for all pci-e 1.1 boards. I think pci-e 2.0 boards can supply 150w via the slot and so theres 225w available.

Think about it this way, at 1.35v compared to stock of 1.15v, the power consumptiion has increased 38% before any clock increase. At 1.4v this is 48%. Say you hit 800mhz for the core, thats a combined increase of 76% and 89% respectively.

At a peak wattage of 109w

http://www.xbitlabs.com/images/video...4850_power.gif

and if we attribute 80% of that to the core. A 76% increase in core power consumption is an increase of 66w. This is a peak wattage of 175w. For the 2nd scenario it would be even higher.

NB the 80% attributation to the core is a pure guess. Also, if the card xbitlabs used has a lower than 1.15v stock voltage, it would be even higher.

Thanks, its a shame there are no pci-e 2.0 boards with 2 x16 slots yet. And probably explains why the 4870 has 2 x 6pin.

There are people running over 1.3v successfully on these cards though, unless they havent tried fur bench.
07-09-2008, 12:36 AM
biohead

Quote:

Originally Posted by Devious

Thanks, its a shame there are no pci-e 2.0 boards with 2 x16 slots yet. And probably explains why the 4870 has 2 x 6pin.

There are people running over 1.3v successfully on these cards though, unless they havent tried fur bench.

X38/X48 are 2*16x pci-e 2.0

btw flashed with 1.263v bios (giving 1.2v) and went from stock 670mhz to 740mhz core. 1075 mem. seems alright.
07-09-2008, 12:53 AM
Devious

Quote:

Originally Posted by biohead

X38/X48 are 2*16x pci-e 2.0

btw flashed with 1.263v bios (giving 1.2v) and went from stock 670mhz to 740mhz core. 1075 mem. seems alright.

of course yeah, sorry i wrote that just after crawling out of bed.

So it cant be the supplied power from the slot, it must be down to having only 1 x pci-e connector ??

1.2v only gets me around 690core, it will run some games but artifacts in fur bench.
07-09-2008, 01:05 AM
biohead

Quote:

Originally Posted by Devious

of course yeah, sorry i wrote that just after crawling out of bed.

So it cant be the supplied power from the slot, it must be down to having only 1 x pci-e connector ??

1.2v only gets me around 690core, it will run some games but artifacts in fur bench.

1 pcie power connector can supply loads of power. it's the VRMs that get crazy hot. i always scratch the back of my head when people talk about a 75W max from the pcie connector, when not so long ago everyone was obsessed with how many amps their 12V line had. a pcie connector delivering 10 amps means it's supplying 120 watts to the card, it's that simple.
07-09-2008, 01:26 AM
Devious

My vrm's have heatsinks on with a fan blowing on and dont go above 45c. My friend has a 4870 and runs all day at 790/1100 with vrms at 85c +

thats why i put it down to the extra 6 pin
07-09-2008, 01:57 AM
biohead

Quote:

Originally Posted by Devious

My vrm's have heatsinks on with a fan blowing on and dont go above 45c. My friend has a 4870 and runs all day at 790/1100 with vrms at 85c +

thats why i put it down to the extra 6 pin

well parallel power supply adds voltage stabillity. but 690/790 for 4850/4870 respectively isn't much of a strain to the VRMs. could be just a weaker core. start comparing VRM quality at 900+ mhz with 1.4+ volts. just my :2cents:

btw my 740 core is only put to the test with crysis bench 5 loops 1680x1050 high. but i've found it crashes in the 3rd loop when it's unstable (750). probably due to rising temperatures. gonna test 750 with some better cooling (TR SI-128).

[edit] ok ran furmark 1680x1050 8xAA 16xAF for about 15 minutes, it's stable and artifact free. max 73°C load with stock cooler (editted automatic fan speed slope in bios).
07-09-2008, 09:07 PM
zbomb5610

update on my testing at 855/1150 is perfectly stable running rthdribl for several hours at 1.36v under load without artifacts. only 1.1v idle due to the 160/500 setting. temps around 50c load.

3dmark06 14127 (no artifacts)
sm2.0 5969
hdr/sm3.0 7173
cpu score 3150 (e6300 at 3.55)

probably going to run some tests w/ crysis bench. also might pencil mod the memory to see if i can get 1200 stable.
07-09-2008, 09:17 PM
[XC] gomeler

So far I'm doing 905MHz core, 1100MHz memory on a HD4850 with 1.55vgpu under an Arctic Cooling S1 with a ~110cfm fan strapped to the heatsink. No heatsinks on the pwm, chokes, or memory modules. Suspect once I sink the mosfets and chokes and put this under dry ice that 1.55vgpu will yield 980-1000MHz. Mosfets get pretty hot, around 65C according to my k-type probe.
07-09-2008, 11:37 PM
strange|ife

ok in RBE excuse me for im a noob with this tool.

I want to change v from 1.263 a bit higher, not to much since this card is on air. What values do i need to edit out of Clock Info 0-9?

fur benchmark crashes with anything over 825mhz core with 1070mhz memory..anything over 1070 with even a lower cor elike 750mhz crashes..so i found peak overclock on stock voltage. I dont have enough experience with pot's to really want to mess with that, besides its only air cooled

what is good voltage to bump up to maybe get me to 850 core
07-09-2008, 11:44 PM
Achill3uS

Quote:

Originally Posted by [XC] gomeler

So far I'm doing 905MHz core, 1100MHz memory on a HD4850 with 1.55vgpu under an Arctic Cooling S1 with a ~110cfm fan strapped to the heatsink. No heatsinks on the pwm, chokes, or memory modules. Suspect once I sink the mosfets and chokes and put this under dry ice that 1.55vgpu will yield 980-1000MHz. Mosfets get pretty hot, around 65C according to my k-type probe.

nice results, but 1.55v on just air seems a bit high to me, be careful :)
07-09-2008, 11:49 PM
[XC] gomeler

Quote:

Originally Posted by Achill3uS

nice results, but 1.55v on just air seems a bit high to me, be careful :)

Cards will be on air for another hour then dry ice tubes :D
07-09-2008, 11:51 PM
strange|ife

would 1.35Vgpu get me @ 850mhz core? this is my goal for 850 core maybe a tad higher.

just dont want to burn my card out, plan to keep this baby for a while
07-09-2008, 11:52 PM
[XC] gomeler

Quote:

Originally Posted by strange|ife

would 1.35Vgpu get me @ 850mhz core? this is my goal for 850 core maybe a tad higher.

just dont want to burn my card out, plan to keep this baby for a while

With 1.45vgpu I managed 885MHz on my good card, so maybe 1.4v for 850MHz? My garbage card needs 1.55v for 885MHz so it's a tossup :shrug:
07-09-2008, 11:59 PM
strange|ife

what values need be changed in RBE for voltage. I see 0-9 for all the clock settings with vgpu. But kinda of confused on which need changing

thanks
07-10-2008, 05:36 AM
nanohead

I used a template of Gurusan's BIOS, and I'm running on water, so things seem to be ok. However, while I can get through 3DMark ok, when I try and run Crysis or Jericho, I crash hard.

Wonder if anyone has seen similar behavior. I'm using the hotfix 8.6 Cat.

Not sure what the issue is actually. Running 720/1100, seems stable. Although, when I ran 1100 after overdrive set up the mem, I could not complete 3Dmark. 1 of my cards made all the way to 1200 mem, the other to 1140. Maybe I have a lame card in the mem department. Not sure if mem speed does anything anyway other than make us happy :rofl:
07-10-2008, 06:22 AM
biohead

Quote:

Originally Posted by strange|ife

what values need be changed in RBE for voltage. I see 0-9 for all the clock settings with vgpu. But kinda of confused on which need changing

thanks

3,6,7,8,9
07-10-2008, 08:26 AM
zbomb5610

Quote:

Originally Posted by strange|ife

would 1.35Vgpu get me @ 850mhz core? this is my goal for 850 core maybe a tad higher.

just dont want to burn my card out, plan to keep this baby for a while

sorry if you stated this somewhere earlier, but you do have a volt mod correct? you aren't just changing the values in the bios and hoping for 1.36 volts through just editing the bios?

1.36 volts load got me 855/1150 stable.
07-10-2008, 12:41 PM
AliG

hey can you test how much voltage you need for 750 and 800 core? Thanks, I know every card is different, but I'd like a general idea
07-10-2008, 02:18 PM
zbomb5610

Quote:

Originally Posted by AliG

hey can you test how much voltage you need for 750 and 800 core? Thanks, I know every card is different, but I'd like a general idea

1.3v should do it, just give it a go and test it. you might need more than 1.3 or maybe a little under 1.3, no way to find out on your card until you do it yourself.
07-10-2008, 06:48 PM
Factotum

I tested overcloking 4850 in 3DMark06, voltmod, cooling with Accelero S1
625/2000 (default): 12 745
800/2200: 14 238
800/2400: 14 608
825/2400: 15 375
830/2400: 15 033
840/2450: 15 401
850/2000: 14 057
as seen after 825 MHz for GPU performance has ceased to grow, even more at 830 MHz on the core see failure. I repeated the tests with 825 MHz and 830 MHz - the differences were within the limits of errors
I think in DX10 frequency dependence productivity of GPU / GDDR will be similar
07-10-2008, 09:17 PM
barong

can i get 800 for core without voltmod, only from bios?
how much is the maximum core without voltmod?
my card is HIS 4850
07-10-2008, 09:22 PM
Confused_User

Quote:

Originally Posted by barong

can i get 800 for core without voltmod, only from bios?
how much is the maximum core without voltmod?
my card is HIS 4850

without voltmod ur probably looking at around 720-750ish with good cooling
07-10-2008, 09:28 PM
barong

voltmod with pencil, can anyone teach me how to use DMM, sorry if its OOT
07-11-2008, 12:55 AM
zbomb5610

currently testing 1225 on the memory @ 2.07v, it was unstable at 2.26v and 2.17v, and i couldn't do over 1150 on stock voltage, so i think 2.07 is barely higher than stock but it is working like a champ so far.

edit ** now testing 1250 on the memory using rthdribl. no artifacts so far.

couldn't pass 3dmark06 w/o getting artifacts using 1250, but 1225 passed no problem w/ zero artifacts.
07-11-2008, 01:08 AM
alioth

hi allll :)
finally i have the 4850 :D:D:D
i want to know how much can i clock the card in relax..in daily! with this system:

e6420 up to 3.2 ghz
xigmatek s1283
asus p5q-pro
vga, you know :p:
accelero s1 with 2 92mm(more or less 30-40 cfm each)
case: antec nine hundred with 3 120 on the front

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