New Motherboard, lower hashrate :-( Why?

[picsnapr]

Hi friends,
I've been mining for a couple of months now, with a basic rig setup of single GPU R9 380x on a Gigabyte 970 AM3+ motherboard (all pre-used hardware).
My setup and settings are posted here for details.
After a recent thermal paste renewal on the GPU heatsink, and adding a couple of fans to the casing, I was getting a decent ~25.3 MH/s on this setup. But few days ago, the motherboard went kaput and the PC just went dead. Ofcourse I verified the Mobo as the culprit, by plugging in another PSU.
Now I got another used Mobo, an MSI 970A-G43, keeping all the rest hardware the same. The PC is back online now, and after installing/updating all the required drivers, as I started mining again, the hashrate now showing just ~20.07 MH/s. I even checked the Bios settings of the new Mobo and set everything to "no power saving" and set for high performance, but don't see any improvements to the hashrates.
Now 'm really at my wit's end; can't figure out why the hashrate dips so low all of a sudden?
Can any one please point out what I can check/change to get my 24-25MH/s back again?

[Geraldo]

Have you had the same tune-up with the last one?

As I read your post, you were only "checked the Bios settings of the new Mobo and set everything to "no power saving" and set for high performance." Have you tried to OC'ing your card, by the way?

[awais3344_1]

Is the mobo new or used one? I have used old mobos and never had such a problem. Like the last poster said check your oc settings again. It's likely that they're not working or not setup.

[picsnapr]

Is the mobo new or used one? I have used old mobos and never had such a problem. Like the last poster said check your oc settings again. It's likely that they're not working or not setup.

Thanks. I've not actually OC'd anything, as I'm not that good on cooling part. With the current setup itself, the temps run into 73-74 deg C, as 'm in a hot tropical country.
Btw, I did figure out the issue. While installing the new drivers for the mobo, I also updated the GPU adrenalin driver. That was the culprit. I DDU'd the drivers, and re-installed the previous working version, and walla! I'm back to 25.1 MH/s on the rig. 

[Geraldo]

Congratz buddy,

Which driver that was giving your R9 rig the best performance? I'm using 16.9.2 for my R9 rigs (290, 290X, 390, 390X, 295X2).

Your temps were quite good, while you are using R9 series on the tropical country. I have ever run my R9 Rig above 85. 

[Rasanders22]

reinstall the drivers. I've had issues with drivers going crazy when switching out hardware.

[Turkish88]

Try to reinstall chipset drivers.
Other reason can be dry out capacitors.  Capacitors lost their capacity with time.