Acer Aspire TimelineX 3820TG mods/tweaks ONLY!

According to middleton three fan tables here are most likely for different CPU types (eg. i3, i5, ???) in order to have different speeds for different CPUs. But do you mean both fans was run at max speed after flashing? In such case he is definitely wrong.
I'll try to modify tables one by one.
LEDs are really concerns me. I wonder maybe EC uses this method to indicate that something wrong with firmware?

There is no formula here. EC values from 0xA8/0xA9 are already temp in Celsius.
I also wanted to find Temp tables in firmware, but still can't find time to determine temps when Fan speeds are changed.

 

Yes, both fans were running full speed after flashing to modded EC. Different fan tables for CPUs doesn't make much sense, since in some models Acer puts CPUs other than i3/i5/i7 (P4200 or something?). Also, the fan speeds are all identical, so why store it in 3 places?

Yes, I think so too. Unless, one of those fan tables is not really a fan table, but has LEDs or backlight control or settings? It is highly unlikely, but it is possible.
Maybe it indicates that the firmware checksum failed?

Excellent!

I will try and look into it today, no promises though.

 

Well, I have 2 news: good and bad.

The bad is: there is a checksum. I have changed only one speed D0 -> FF and got same symptoms as yours: no backlight, LED blinks + no mouse . Was really scared .
But the good: it seems like to be a XOR. I have swapped D0 with FF from another table (first table became FF FF ..., second: D0 D0 ...) and all have flashed fine.

 

When did I tell you that the three fan tables in Acer's EC are for different CPU types. I haven't said that. Though it may be so. Acer uses the reference EC code from Insyde software. It's possible that Insyde created universal code for all different CPUs but Acer simply doesn't use this feature. Maybe Acer just decided to use only one fan table for all CPUs. But it's just my assumption.

By the way some Toshiba laptops have 12 fan tables in the EC firmware and all 12 tables are different. In this case the tables are definitely for different CPU types.

And just for your information: I've found temperature tables in Acer's EC firmware. I bet you can find it too it's very easy.

 

Why don't you tell and save us a huge amount of time?

Great! Do you know where that checksum is stored? We could do a hexcompare on v1.13 and v1.19 firmwares. They changed the way fan behaves, so maybe we can find where checksum changed?

 

I've found it only today and immediately posted information here. Search "THM01" string in the firmware. Right after that string you can find three temp tables. At least one of them is different. So if we put two and two together, then conclusion is the following:

There are three cooling strategies in the firmware for three different hardware configurations but Acer prefers to change temperature thresholds instead of changing the fan speeds (as we know all three fan tables are the same).

By the way, I can try to find the checksum if you wish.

 

Wow, thanks a lot! That makes sense. But why changing all 3 tables changed both CPU and GPU fans? Does that mean 1 table controls both fans or there is a separate table for GPU fan? We should probably test it more and see what table is active and what it controls.

Yes, can you look for checksum please? It is probably something generic.

In the pdf provided in KBC folder, it mentions that there is an option to dump EC firmware to a file. What if we flash to modded firmware with incorrect checksum and then dump it to a file. Would that give us a firmware file with a "fixed" checksum? I have a feeling it wouldn't, just throwing the idea out there.

 

Sorry. Have incorrectly interpreted your words. My mistake .

It would be great because this is some unusual XOR. Here is my findings:
This is orig speed table:
FF D0 B6 9E 81 6F 6F 6F 6F
1 step:
FF 9E B6 D0 81 6F 6F 6F 6F - Flashed OK
2 step:
FF FF B6 D0 81 6F 6F 6F 0E - Flashed OK
0E = 9E xor FF xor 6F
3a step:
FF FF FF D0 81 6F 6F 6F 47 - Flashed FAILED
47 = B6 xor FF xor 0E
3b step:
FF FF FF D0 81 6F 6F 26 0E - Flashed OK
26 = B6 xor FF xor 6F

Very strange...

 

I believe GPU fan has its own tables: I've changed all 3 tables with values above, but GPU fan still turns on with different speed (according to RW everything).

 

I've just found nine temperature tables:

Code:

1) 302B 3531 3A36 423C 5544 6253 6769
2) 2D28 322F 3A34 423C 4944 554B 585A
3) 302B 3531 3A36 423C 5544 6253 6769
4) 3C38 3F3D 4340 4844 4D49 574E 5C5D
5) 2B26 342D 3E36 4740 5049 5F56 6062
6) 3C38 3F3D 4340 4844 4D49 574E 5C5D
7) 2E2B 342F 3B35 463D 5448 6756 696A
8) 302C 3632 3E38 4640 5048 6964 6A6C
9) 2E2B 342F 3B35 463D 5448 6756 696A

And it seems that quantity of fan tables is above three:

Code:

01) FF D0 B6 9E 81 6F 6F 6F 6F B0 
02) FF D0 B6 9E 81 6F 6F 6F 6F B0
03) FF D0 B6 9E 81 6F 6F 6F 6F B0
04) FF BD A9 99 8C 7E 7E 7E 75 97
05) FF BD A9 99 8C 7E 7E 7E 7E 7E
06) FF 84 75 66 62 7B 7B 7B 7B B0
07) FF 84 75 66 62 7B 7B 7B 7B B0
08) FF 84 75 66 62 7B 7B 7B 7B B0
09) FF D6 B6 9E 9E 81 81 81 81 B0 
10) FF D6 B6 9E 9E 81 81 81 81 B0
11) FF D6 B6 9E 9E 81 81 81 81 B0

Maybe GPU fan speeds are in the additional fan tables.
Come on 3820TG owners, patch them all .