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What part does "TDP" play...?

Coldblackice

Coldblackice

[H]ard|Gawd
Joined
Aug 14, 2010
Messages
1,156
Regarding modding a 7950's BIOS, I'm still fuzzy as to what the "TDP (W)" (PowerTune) value is, and what purpose adjusting it serves...?


(For reference, I'm running a Sapphire 7950 3GB Reference, 54.5% ASIC, 1140/1675 OC)
 
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TDP means Thermal design power, which is how much heat in Watts can the GPU output, which dictates what kind of electrical and cooling systems are needed to support that level of use.

Higher TDP = more power consumed, more heat, and usually more performance.

Lower TDP = less power, less heat, less performance, etc.
 
Slight correction, TDP doesn't determine what PSU and electrical system you need.

TDP only affects how much cooling you need, if card has 300W TDP then you need a cooling system that can remove 300W.

A card could have a TDP of 300W and draw 1000W whilst a different card could have a TDP of 300W and only draw 350W.

TDP =/= Power usage

TDP = Max heat output



And 54.5% ASIC is really bad, that card is going to need a lot of VCore to OC and produce a lot of heat.
 
If you have high TDP chip vs a low TDP chip, I believe that the high TDP chip will have beefier power delivery components to support the higher load, as more power will be converted to heat, correct?
 
cwaffles said:
If you have high TDP chip vs a low TDP chip, I believe that the high TDP chip will have beefier power delivery components to support the higher load, as more power will be converted to heat, correct?
Click to expand...

Yes, but you should never base your power systems of TDP.
 
People take the whole ASIC thing too literally. It certainly has some kind of connection to overclocking. For example, I have an extremely high ASIC score of 90.6% on my 7950, and stock voltage is extremely low at 1012mv at 950 mhz stock. It can do 1000mhz at that stock voltage. It can do 1210mhz core on 1112mv which is really low, but it still produces a lot of heat. I would NEVER be able to cool anything over 1140 on air, even though that's comparably low voltage (many reference cards run 1.2 - 1.25v and run pretty coolly), It has something to do with ASIC score I believe.
 
Gumbi10 said:
People take the whole ASIC thing too literally. It certainly has some kind of connection to overclocking. For example, I have an extremely high ASIC score of 90.6% on my 7950, and stock voltage is extremely low at 1012mv at 950 mhz stock. It can do 1000mhz at that stock voltage. It can do 1210mhz core on 1112mv which is really low, but it still produces a lot of heat. I would NEVER be able to cool anything over 1140 on air, even though that's comparably low voltage (many reference cards run 1.2 - 1.25v and run pretty coolly), It has something to do with ASIC score I believe.
Click to expand...

How much ASIC quality affects you depends on what type of overclocker you are, if you go for the high 1.3Ghz overclocks then you will want a very high ASIC quality.
 
So is 1140/1675 with a 54.5% ASIC T 1.25 not very good? I've tried setting the voltage lower, but no matter what I do, it jumps to 1.25 when 3D mode kicks in.


Further, I'm wondering what the purpose is in editing the "TDP (W)" value in the card's BIOS...? I can understand editing clocks and voltages across the various PowerPlay states, but I don't follow what setting the TDP(W) (under "PowerTune") is for.

(I gather that that setting the TDP percentage under "OverDrive" is telling the card's inhibitor to allow for a higher heat/power output of TDP.)
 
Coldblackice said:
So is 1140/1675 with a 54.5% ASIC T 1.25 not very good? I've tried setting the voltage lower, but no matter what I do, it jumps to 1.25 when 3D mode kicks in.
Click to expand...

How are you adjusting voltage?

Are you using a Boost 7950? The reason is 1.25v is the boost voltage. If you just adjust the regular voltage (if that is what you are doing in bios) that would be the issue. The clock speed you are adjusting is the boost clock speed. I've heard this boost voltage can't actually be adjusted in the bios properly, you have to do it via software.

The 7950 Boost is better for stock performance numbers but I think it introduces extra issues that a problematic for people who are actually tweaking.
 
limitedaccess said:
How are you adjusting voltage?

Are you using a Boost 7950? The reason is 1.25v is the boost voltage. If you just adjust the regular voltage (if that is what you are doing in bios) that would be the issue. The clock speed you are adjusting is the boost clock speed. I've heard this boost voltage can't actually be adjusted in the bios properly, you have to do it via software.

The 7950 Boost is better for stock performance numbers but I think it introduces extra issues that a problematic for people who are actually tweaking.
Click to expand...

Up till now, I've been adjusting the voltage through only Afterburner -- however, after seeing that the 3D voltage never seems to change no matter what I set, I gave up on messing with voltages. I haven't yet modded the BIOS, as I'm still trying to understand the specifics of upping/lowering TDP values.

Hmm, I'm pretty sure I'm not using a boost-7950, just a "regular" Sapphire 7950 "Dual-x".

I'd like to mod the bios and do the overclocking that way in order to remove an extra variable in the middle (Afterburner), hopefully providing better stability and less hassle. But there seems to be a whirl of variables/info/opinions on what to change (and how much).
 
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